From the important character of these duties as connected with the means essential to a national defence, and the vast amount of money expended in these operations, it is evident that a high order of acquirements should be deemed necessary to qualify one to perform the duties of a military engineer. This officer requires a knowledge of chemistry, to guide his choice of materials for mortars, cements, and mastics; of mineralogy and geology, for selecting stone; of botany, for timber and the means of preventing its decay; of mathematics, in laying out his work and calculating the thickness and stability of his walls, embankments, &c.; of mechanical philosophy, in constructing his machinery; of military engineering, in his plans of fortifications; and of all the higher branches of military science, in selecting positions for these works, such that they shall have the proper relations to the means of national defence, and to the grand operations of armies in the field. The avenues to appointment to this corps are guarded, in most European armies, with special care, to prevent the influence of money, politics, or family connections; and in our own army it is now specified by law of Congress, that the vacancies shall be filled only from the most distinguished graduates of the military academy. Formerly our service suffered most severely from the employment of incompetent persons, introduced through political influence from civil life, and foreign charlatans, the refuse of European armies. Many of our earlier military works (as will be mentioned hereafter) were modelled upon systems for a long time discarded by the profession in Europe, and even some of those which have been constructed within the last thirty years are made of such wretched materials and workmanship, that they are already crumbling into ruins. While the existing laws and regulations seem well calculated to prevent the recurrence of similar abuses and errors, it nevertheless can be shown that the organization of this arm of our service requires modifications and extensions to give it the requisite degree of efficiency, and to economize the public expenditures.

The wars of Louis XIV. first led to a regular military organization, and a regular system of defence. In these wars the engineers received great development, and have ever since occupied a prominent position as parts of an army organization. We therefore find in all the great sieges and battles of this era a large and continually increasing number of engineers and engineer troops, this force being gradually augmented as the true principles of war became better understood, and as the wants of the service required. Even in the earliest of these battles we find the engineers taking a prominent and distinguished part. In the war of 1688, twenty-four engineers were killed and wounded at the siege of Philipsbourg, eighteen at Namur, eight at Huy, ten at Charleroi, eight at Ath, thirty at Barcelona, &c. Such losses were good proofs of the usefulness of these officers, and before this war was closed, their number was increased to six hundred; and in 1706 the army contained eight brigades of engineers and four companies of miners.

The engineer corps being partially disbanded in the early part of the French Revolution, great difficulty was experienced in reorganizing it and in finding competent men to supply the places of those who had been driven into exile or sacrificed during the reign of terror. Energy and activity, combined with republican zeal, could supply the place of skill in the other arms, but the science of the engineer could not be acquired in a day.

In 1799, the staff of the engineer corps consisted of four hundred and forty-nine officers, without including the general officers, commanding departments, or those connected with the engineer troops. The same organization was continued in 1804. The engineer staff of the French army now numbers four hundred and thirty-two officers. We have in our service forty-three engineer officers, for staff duty, who are now engaged in the construction and repairs of some sixty or seventy fortifications, and other works of a civil and military character.

II. Engineer Guards, or Fort-Keepers, are a class of men charged with the general care of forts, and all public property deposited in the several engineer depots and garrisons, and in the public works during their construction.

There are five hundred and fifty of these "gardes du Genie" in the French army, who rank next the sub-lieutenants of engineers, and are assimilated with the sub-lieutenants of infantry in the hospitals, marches, &c. In our service we have no engineer guards or fort-keepers.

This defect in our organization has been the cause of serious inconvenience, and the consequent waste of public property. The expense of hiring civil agents for this purpose has more than trebled the cost of supporting a suitable number of non-commissioned guards to maintain the good order and efficiency of our forts, in the absence of engineer officers, and to preserve and keep in repair the military implements and stores connected with this department of the army. It has already been shown that we have fifty-eight of these guards for the artillery service, and it really seems somewhat singular that the engineers, with a much greater amount of public property in their charge, are allowed no assistants of this kind.

III. Engineer artificers are a class of men employed in the practical operations of constructing forts and other military defences, and in making and repairing all the implements used by the engineer troops in the operations of sapping and mining, in crossing rivers, in constructing field-defences, and in the attack and defence of fieldworks.

As very few new fortifications are now required in France, the services of engineer artificers are less necessary and important than in our service, where large sums of money are annually expended upon military defences, There are, however, in the French army a corps of engineer artificers, consisting of eight officers and a cadre of fifty-four non-commissioned officers, with a variable number of privates, organized into two companies. But in our army we have no regular engineer artificers! In our artillery service we have three hundred and thirty enlisted artillery artificers. If these are useful and necessary to the artillery service, which no one doubts, for still stronger reasons would it be advantageous to the public service to employ at least an equal number of enlisted engineer artificers on our fortifications; for the annual expenditure of public money is here much greater than in the corresponding branch of the artillery service.

IV. Engineer troops are divided into three classes—1st, sappers and pioneers; 2d, miners; and 3d, pontoniers.

In the French army of 1799, there were four battalions of sappers, consisting of 120 officers and 7,092 men. In 1804, Napoleon organized five battalions of these troops, consisting of 165 officers and 8,865 men. Even this number was found insufficient in his campaigns in Germany and Spain, and he was obliged to organize an additional number of sappers from the Italian and French auxiliaries. The pioneers were then partly attached to other branches of the service. There is, at present, in the French army a considerable number of sappers or pioneers detached for the service of the infantry regiments, three companies of sapeurs-conducteurs, and forty-two companies of sapeurs. In the French army of 1799, there were six companies of miners, consisting of 24 officers and 576 men. In 1804, Napoleon increased these troops to nine companies, containing 36 officers and 864 men. The present French peace establishment contains six companies of miners, organized much the same as under Napoleon. In the French army of 1799 there were two regiments of pontoniers, of 38 officers and 960 men. But this number was found too small in the remaining campaigns, and the deficiency was temporarily supplied by organizing sailors for these duties. In the present French army organization, there are eleven companies of pontoniers, forming a regiment of sixty-three officers.

We have in our service no sappers, miners, or pontoniers, and, in case of war, would be found without the means of executing any military works, or performing any military operation which would require engineer troops.

In the preliminary stages of army organization under Louis XIV., infantry troops were detailed as sappers, and instructed in these duties by the engineers. This irregularity of service soon caused difficulties and losses, and the evils springing from it were so great, that Vauban urged the propriety of a separate organization. In 1670 he officially recommended to the king to establish a regiment of twelve hundred sappers and ouvriers, and in a subsequent report on the value of these troops, used the following language: "They would be useful in peace as well as in war, and would be the means of saving much in all fortifications where they should be employed. In fact, I have not the least doubt that they would save annually to the king much more than their pay. I assert all I have said on this subject with as much confidence as if I had seen the result; and I can, with the same certainty, add, that this small troop will be the means of saving large numbers of good engineers and brave officers and soldiers, from the stern necessity to which we are reduced of exposing, almost always, the laborers and those who support them; which necessity would not arise had we at command a sufficient number of this kind of workmen well instructed. To such a degree have I felt the necessity of sappers, at every siege at which I have been present, that I have always had reason to repent of not having more urgently solicited the creation of this company."

Such are the views of the greatest of military engineers, a man who fought one hundred and forty battles, conducted fifty-eight sieges, and built or repaired three hundred fortifications. His anticipations of the usefulness of engineer troops were fully realized, and they have ever since received the most careful attention, and now form, as has just been shown, one of the most important and efficient arms in the French service. The fortifications constructed by the engineers, as organized by Vauban, have ever since constituted one of the principal elements of the French military power.

In the wars of Napoleon there are innumerable instances in illustration of the delays and disasters attending the operations of armies not supplied with engineer troops; and, on the other hand, the advantages resulting from their services when properly organized and instructed. We have already pointed out the influence which the fortifications in the hands of the French exerted on the results of these wars, and the fatal consequences to the Allies of neglecting these works of national defence. Every student of military history will immediately call to mind the influence of Savona, Coni, Mondovi, Ceva, Govi, Alessandria, Tortona, Pizzighitone, Peschiera, Mantua, Palma-Nuova, Osopo, Klagenfurth, &c., in the campaigns of 1796-7; of Genoa, Port Bard, the fortifications of the Var, Ulm, Ingoldstadt, &c., in 1800; of Milan, Turin, Mantua, Roco d'Aufo, Genoa, Alessandria, &c., in 1805; the importance of Kehl, Cassel, Wesel, &c., to the French in 1806, and the fatal consequences to the Prussians in that campaign, of their total and culpable neglect of their own fortifications.

All military historians speak of the influence of fortifications in the Peninsular campaigns: those which had been given up to Napoleon previous to the opening of hostilities, contributed very much to the success of his arms, while those which were retained by Spain and her allies, contributed in an equal degree to hamper and embarrass his operations. Some of these, like Saragossa and Tarragona, with their broken walls and defective armaments, kept the enemy in check some sixty days each, and did much to weaken the French power in the Peninsula.

Temporary or field-fortifications also had an important influence here. The lines of Torres-Vedras, the field-works of Ronda, the intrenched camps of the Pyrenees, Bayonne, Toulouse, &c., are examples under this head. In fact, field-works played a most important part in all of Napoleon's wars. We might mention the redoubt of Montenotte, the intrenchments at Milesimo, the batteries of Lobau, the field-defences of Hougomont, La Haye-Sainte, and Papelotte at Waterloo, and numerous other cases equally striking. Just before the battle of Waterloo, Wellington employed some eighteen thousand peasants and two thousand horses, under the direction of British officers of engineers. In speaking of these defences, Colonel Pasley says: "It may be easily conceived that to have directed such a great body of workmen to proper advantage, by means of a few officers of engineers, would have been impossible, but for the system adopted of subdividing the various works among the non-commissioned officers and privates of the engineer troops, each of whom was made responsible for laying out the details of his own portion, and for the direction of a party of from twenty to one hundred men, or even more, according to circumstances."

But to return to the Peninsular war. These campaigns exhibit in strong colors the advantages derived, on the one side, from a well-organized engineer corps, and the losses, delays, and defects suffered on the other, until the defects of the organization were remedied. Napoleon entered Spain with a well-appointed army, and soon, through strategy and well-directed force, gained possession of the important fortresses of the Peninsula; seizing in this way the strategic routes and important geographical points, he was enabled to retain possession of the country for eight years, in spite of the numerous forces arrayed against him, the absence of himself and his best generals in Germany, and the great inefficiency of Joseph and of many of his generals. These fortifications were old, and of strength inferior to modern works of defence, but it required years and the expenditure of millions in blood and treasure to expel from the country those who had possession of them.

For the first five years of this war the English struggled with a most imperfect army organization.[37] When "the first serious siege," says Napier, was undertaken by the British army, "to the discredit of the English government, no army was ever so ill provided with the means of prosecuting such an enterprise. The engineer officers were exceedingly zealous; and many of them were well versed in the theory of their business. But the ablest trembled when reflecting on their utter destitution of all that belonged to real service. Without a corps of sappers and miners, without a single private who knew how to carry on an approach under fire, they were compelled to attack fortresses defended by the most warlike, practised, and scientific troops of the age."

[Footnote 37: In a letter dated February 11th, 1812, Wellington wrote to the Secretary of State as follows:—"I would beg leave to suggest to your lordship the expediency of adding to the engineer establishment a corps of sappers and miners. It is inconceivable with what disadvantages we undertake any thing like a siege for want of assistance of this description. There is no French corps d'armee which has not a battalion of sappers and a company of miners; but we are obliged to depend for assistance of this description upon the regiments of the line; and although the men are brave and willing, they want the knowledge and training which are necessary. Many casualties among them consequently occur, and much valuable time is lost at the most critical period of the siege."]

"The best officers and finest soldiers were obliged to sacrifice themselves in a lamentable manner, to compensate for the negligence and incapacity of a government, always ready to plunge the nation into war, without the slightest care of what was necessary to obtain success. The sieges carried on by the British in Spain were a succession of butcheries; because the commonest materials, and the means necessary to their art, were denied the engineers." Colonel J.T. Jones writes in nearly the same terms of the early sieges in the Peninsula, and with respect to the siege of Badajos, adds in express terms, that "a body of sappers and miners, and the necessary fascines and gabions, would have rendered the reduction of the work certain."[38] Soon after this siege a body of engineer troops arrived from England, but their number was insufficient, and Wellington, having learned by sad experience the importance of engineer troops, ordered a body of two hundred volunteers to be detached from the line, "and daily instructed in the practice of sapping, making and laying fascines and gabions, and the construction of batteries, &c." The siege of Ciudad Rodrigo, which immediately followed this organization, was conducted with greater skill and success than any other till nearly the close of the war; and all military writers have attributed this result to the greater efficiency of the engineer force engaged in the siege. This arm was now gradually increased, and the last year of the war the engineer force with the English army in the field consisted of seventy-seven officers, seven assistant-engineers and surveyors, four surgeons and assistants, one thousand six hundred and forty-six sappers, miners, artificers, &c., one thousand three hundred and forty horses and one hundred and sixty carriages.

[Footnote 38: Colonel Pasley states that only one and a half yards of excavation, per man, was executed in a whole night, by the untrained troops in the Peninsular war; whereas an instructed sapper can easily accomplish this in twenty minutes, and that it has been done by one of his most skilful sappers, at Chatham, in seven minutes!]

During all this time the French furnished their armies in Spain with well-organized engineer forces. We have endeavored to form a comparison of the number of French engineers and artillerists employed on these peninsular sieges. But from the loose manner in which these details are usually given by historians, it is almost impossible to distinguish between the two. Both are not unfrequently given under the same head, and when a distinction is apparently kept up, only the engineer staff is mentioned under the head of engineers—the sappers, miners, artificers, the train, &c., all being put down as artillery. In the following table we have endeavored to arrange them as is done in our own army. The trains of both arms are left out, for frequently that of one arm performed the duties of the other. Moreover, in our service a portion of these duties of engineer and artillery trains is performed by the quartermaster's department. For those who wish to know the exact organization of the French engineer train, we give it as it existed in 1811, viz.:—seven troops, each troop consisting of three officers, one hundred and forty-one non-commissioned officers and privates, two hundred and fifty horses, and fifty wagons, conveying five thousand two hundred and seventy intrenching tools, one thousand seven hundred cutting tools, one thousand eight hundred and two artificers' tools, two hundred and fifty-three miners' tools, and eight thousand three hundred and eighteen kilogrammes' weight of machinery and stores, each article being made to a particular pattern. The pioneers in Spain acted sometimes with one arm and sometimes with the other, and we have assigned them accordingly in the table. The pontoniers, however, in our service are included with the engineers; we have therefore put them, in our table, in the same column with the engineers.

Engineer Artillery staff, Total Total of staff, sappers, horse and foot of artillery miners, artillery, engineers, staff, horse pontoniers, ouvriers, and sappers, and foot and pioneers. pioneers. miners, artillery, Name of Siege. pontoniers, ouvriers, and and Offic. Men. Offic. Men. pioneers. pioneers. Saragossa, 86 1189 90 1276 1275 1360 Rosas, 21 211 232 461 Girona, 54 603 62 1299 657 1361 Astorga, 7 91 17 427 98 444 Lerida, 15 316 11 208 331 219 Meguinenza, 31 278 312 136 1st Ciudad Rodrigo, 34 441 475 1019 Almeida, 34 489 523 1019 Tortosa, 43 429 32 381 472 413 Tarragona, 50 681 46 701 731 747 Olivensa, 10 106 116 186 1st Badajos, 25 707 41 699 732 740 Tarifa, 12 235 17 148 247 165 Peniscola, 13 138 9 183 151 192 2d Ciudad Rodrigo, 3 12 8 160 15 168 2d Badajos, 9 256 265 268 Burgos, 4 124 3 126 128 129 Castio Udiales, 5 68 8 197 73 205 St. Sebastian, 13 248 7 166 261 173

From this table it appears that the ratio of the two arms at these sieges, making the comparison on the basis of our own organization, is about the same as for the present French army in Algeria, or a little more than five of engineers to six of artillery.

Thus far we have spoken of the field-operations of engineer troops in connection with fortifications, alluding only incidentally to the use of military bridges and the passage of rivers. In the early wars of the French Revolution the want of pontoniers was severely felt, and from the deficiency of this branch of service, the operations of the French generals were on several occasions very much restricted. The evil was afterwards remedied in a great degree by the introduction of several battalions of ponioniers in the regular army organization. On many occasions, during his wars, did Napoleon feel and acknowledge the importance of these troops; but on none, perhaps, was this importance more clearly shown than in the passage of the Beresina during his retreat from Moscow with the wreck of his army. The Russians had cut the bridge of Borisow and taken position in great strength on the right bank of the river, both at this point and below; the French, wearied with long and difficult marches, destitute of artillery, provisions, and military stores, with a wide and deep river in front, and a powerful enemy on their flank and rear, benumbed by the rigors of a merciless climate, and dispirited by defeat—every thing seemed to promise their total destruction. "General Eble," says an English general officer, in his remarks on this retreat, "who, from the beginning of the campaign, had made all the arrangements for the equipment and construction of military bridges, was specially charged with the important duty of providing for the passage of this river; and he discharged that duty with a degree of forecast and ability to which certainly Napoleon owed his escape and the wreck of his army its safety. General Eble had begun to prepare, at Smolensko, for the difficulties which he foresaw in this operation. He formed, with every care, a train sufficient for the transport of all the tools and stores that might be required; and, further to provide against casualties and accidents, every man belonging to the companies of pontoniers was obliged to carry from Smolensko a tool or implement of some kind, and a proportion of nails: and fortunate was it for the army that he did so; for such was the difficulty in getting through the carriages containing stores, that only two forge-wagons and six caissons of tools and nails could be preserved. To these the general added a quantity of iron-work taken from the wheels of carriages that were abandoned on the march. Much was sacrificed to bring off these valuable materials for making clamps and fastenings, but, as Segur observes, that exertion 'sauva l'armee.'"

But it is not always in the possession of a thing that we are most likely to appreciate its utility; the evils and inconveniences resulting from the want of it not unfrequently impress us most powerfully with its importance and the advantages to be derived from its possession. A few examples of this nature, drawn from military history, may be instructive. We need not go back to the disastrous passage of the Vistula by Charles XII., the failure of Marlborough to pass the Dyle, and Eugene to cross the Adda in 1705, nor of the three unsuccessful attempts of Charles of Lorraine to cross the Rhine in 1743. The wars following the French Revolution are sufficiently replete with useful instruction on this subject.[39]

[Footnote 39: Before recurring to these, it might be useful to give one example, as it is often referred to, in the campaign of 1702. It was deemed important for the success of the campaign to attack the Prince of Baden in his camp at Friedlingen. Accordingly, a bridge was thrown across the Rhine at Huningen, the passage effected, and the victory gained. But Villars was several times on the point of losing all for want of a sufficient ponton equipage. Having but a single bridge, the passage was necessarily slow; the artillery and stores were frequently interrupted by the infantry hurrying to the field of battle; disorder ensued, and the whole movement was retarded; Villars could bring only a small part of his artillery into action, and towards the close of the battle the infantry were in want of ammunition: moreover, the whole operation had nearly failed from the attempt of the enemy to destroy this bridge, but the skill of the French pontoniers saved it. We here remark, 1st, the passage secured to Villars an important victory; 2d, from having an inefficient bridge-equipage his whole army was placed in great peril, and the operation had nearly failed; 3d, if the Prince of Baden had possessed a skilful corps to oppose that of Villars, this single bridge would have been destroyed, and the army cut to pieces; 4th, the skill of the little corps of French pontoniers saved the bridge, and of consequence, the army.]

In 1794 so great was the disorder in the direction of affairs, that the boats of the bridges across the Wahal and the Rhine were disposed of for commercial purposes; and in the beginning of 1795, says Jomini, "the conquerors of Belgium and Holland had not even a bridge equipage, at a time too when the success of the campaign depended solely on the means of crossing a river." A few boats were procured from the Wahal and the Meuse, and others manufactured in the forests of the Moselle; but "these operations consumed precious time, and four months thus passed away in preparations." Even after other things were all ready, the army was obliged to wait thirty days for the arrival of boats for ponton bridges; during this delay the Austrians strengthened their position, and with very little exertion they might easily have prevented the passage.

In 1796, profiting by the errors of the former campaigns, the French collected more suitable bridge equipages, and the two armies passed the Rhine at Neuweid and Kehl without loss or delay. The latter of these passages has often been referred to as a model for such operations, and certainly does credit to the general who directed it. But Moreau's bridge equipage having been destroyed during this disastrous campaign, his operations the following year were considerably delayed in preparing a new one, and even then he was under the necessity of seizing all private boats that could be found within reach; but the difficulty of collecting and using boats of all sizes and descriptions was so great as entirely to defeat his plan of surprising the enemy on the opposite bank of the river. The necessity of co-operating with Hoche admitted of no further delay, and he was now obliged to force his passage in the open day, and in face of the enemy. Undertaken under such circumstances, "the enterprise was extremely sanguinary, and at one time very doubtful;" and had it failed, "Moreau's army would have been ruined for the campaign."

Napoleon's celebrated passage of the Po, at Placentia, shows plainly how important it is for a general to possess the means of crossing rivers. "I felt the importance of hastening the enterprise in order not to allow the enemy time to prevent it. But the Po, which is a river as wide and deep as the Rhine, is a barrier difficult to be overcome. We had no means of constructing a bridge, and were obliged to content ourselves with the means of embarkation found at Placentia and its environs. Lannes, chief of brigade, crossed in the first boats, with the advanced guard. The Austrians had only ten squadrons on the other side, and these were easily overcome. The passage was now continued without interruption, but very slowly. If I had had a good ponton-equipage, the fate of the enemy's army had been sealed; but the necessity of passing the river by successive embarkations saved it."

In the campaign of 1799, the Archduke attempted to pass the Aar, and attacked the French on the opposite side, but for want of suitable equipage his operation was delayed till the enemy had collected sufficient forces to intercept the passage; he was now obliged to enter into a stipulation for a suspension of hostilities, and to withdraw his bridges.

The operations of the French in the campaign of 1800, led to the most glorious results, but their execution was attended with the greatest difficulties. The passage of the Alps was greatly facilitated by the ability of the chief engineer, Marescot, and the skill of the troops under his command; and the facility of passing rivers afforded Napoleon by his pontoniers, had an important influence upon the success of the campaign. "The army of the reserve had many companies of pontoniers and sappers; the pontons of course could not be taken across the St. Bernard, but the pontoniers soon found materials on the Po and Tesin for constructing bridge equipages." Moreau's army in the same year profited well by his pontoniers, in the passages of the Inn, the Salza, the Traun, the Alza, &c., and in the pursuit of the Austrian army—a pursuit that has but a single parallel example in modern history.

The facility with which Napoleon crossed rivers, made forced marches, constructed redoubts, fortified depots, and grasped the great strategic points of the enemy in the campaign of 1805, resulted from the skilful organization of his army, and the efficiency given to the forces employed in these important operations. The engineer staff of the French army at this period, consisted of four hundred and forty-nine officers, and there were four battalions of sappers, of one hundred and twenty officers and seven thousand and ninety-two men; six companies of miners, of twenty-four officers and five hundred and seventy-six men; and two regiments of pontoniers, of thirty-eight officers and nine hundred and sixty men. On the contrary, the enemy's neglect of these things is one of the most striking of the many faults of the war, and his ill-directed efforts to destroy the great wooden bridge across the Danube, and the successful operations of the French sappers in securing it, formed one of the principal turning points in the campaign.

The same organization enabled the French to perform their wonderfully rapid and decisive movements in the Prussian campaign of 1806, and the northern operations of 1807.

In 1809, Napoleon's army crossed, with the most wonderful rapidity, the Inn, the Salza, the Traun, and other rivers emptying into the Danube, and reached Vienna before the wonder-stricken Austrians could prepare for its defence. It was then necessary for the French to effect a passage of the Danube, which was much swollen by recent rains and the melting snow of the mountains. Considering the depth and width of the river, the positions of the enemy, and his preparations to oppose a passage, with the disastrous consequences that would result to the French from any failure in its execution; taking all these things into consideration, Jomini pronounced it "one of the most hazardous and difficult of all the operations of War." Here the fate of the army depended, apparently, upon the skill and efficiency of the engineers and pontoniers, and nobly did they discharge the trust reposed in them. When the pontons failed, tressel-bridges were substituted, and even fifty-four enormous boats were put in requisition. So skilfully were these operations conducted, that Napoleon's immense army crossed over in safety, directly in the face of a superior enemy, and the same day fought the memorable battle of Esling. Forced to retire before numbers vastly superior to his own, Napoleon concentrated his forces on the island of Lobau, and intrenched his position. Surrounded by the broad and deep channel of the Danube, and watched by numerous and skilful enemies, it required the most constant activity and the greatest good fortune to effect a passage. Here the skill and efficiency of the engineers shone conspicuously; a number of bridges were thrown across the river in the face of the Austrians, and against obstacles almost insurmountable; the whole French army passed in safety, and soon put the finishing stroke to that brilliant campaign. So high an estimate did Napoleon attach to the construction of these bridges, that, when the passage was completed, he offered to place Bertrand, the constructing engineer, though of comparatively low rank, at the head of the French corps du genie.

On many occasions during the retreat in 1812-13, from the Beresina to the left of the Rhine, across the Niemen, the Vistula, the Oder, the Elbe, and the numerous other rivers which divide that immense country, the French derived vast advantages from the experience and skill of their engineers and pontoniers, several times whole corps escaping through their means from the grasp of their pursuers. When, however, the disasters of this retreat had absorbed most of the material of the army, and had sadly thinned the ranks of men of skill and experience, they sustained many severe, and, in other circumstances, unnecessary losses. Of this character we may mention the passage of the Elster by the bridge of Lindnau, where, through the ignorance and carelessness of those charged with the mines, and through the want of suitable bridge arrangements, thousands of brave men were buried in the muddy waters of this small river. So sensibly did Napoleon feel this want of bridge equipages, in the winter of 1813-14, that he addressed to his minister of war, on this subject, the following remarkable words: "If I had had pontons, I should have already annihilated the army of Schwartzenberg, and closed the war; I should have taken from him eight or ten thousand wagons, and his entire army in detail; but for want of the proper means I could not pass the Seine." Again, on the 2d of March he wrote: "If I had had a bridge equipage this morning, Bluecher's army had been lost." Whoever will examine the details of the operations of this campaign, will be convinced of the full force of these remarks.

In Spain in 1808, Sir John Moore, in order to assist the native forces, had penetrated so near the army of Napoleon, that retreat became exceedingly difficult, and he was several times on the point of being lost. The English army was at this time very deficient in engineer troops, and Moore suffered much for want of miners to destroy bridges, and pontoniers to construct new ones. In order to cover his retreat and impede the advance of the French, the commander-in-chief, says Napier, "directed several bridges to be destroyed, but the engineers [for want of miners and miner's tools] failed of success in every attempt."

In Soult's retreat, in 1809, he crossed the Duero at Oporto, and destroyed the bridges so as to cut off the pursuit of Wellington. But while Soult, deceived by treachery in his own corps, neglected to guard the river with proper vigilance, Wellington collected boats at different points, crossed over his army, surprised the French, and, had it not been for the singular delay and indecision of General Murray, would most certainly have forced the entire army to capitulate; as it was, his operation produced a decided influence on the campaign, and effected the safety of Beresford's corps. Soult destroyed his artillery and baggage, and hastily retreated through the mountain passes; but his army was again arrested at the river Cavado, and placed on the very brink of destruction, when the brave and skilful Dulong succeeded in effecting a passage at the Ponte Nova; the same daring officer opened, on the same day, a way for the further escape of the French across the Misarella by the Saltador.

In the pursuit of Massena, in 1810, it was important to the English to cross the Guadiana, and attack the French before Badajos could be put in a state of defence. Beresford was directed by Wellington to pass this river at Jerumina, where the Portuguese had promised to furnish pontons; but they neglected to fulfil their engagement, and the army had to wait till Capt. Squire, an able and efficient officer of engineers, could construct other means for effecting a passage. Every thing was done that genius could devise and industry execute; nevertheless, the operations of the army were greatly delayed—"a delay," says the historian, "that may be considered as the principal cause of those long and bloody operations which afterwards detained Lord Wellington more than a year on the frontiers of Portugal."

We might prolong these remarks by discussing the passages of the Ceira and Alva, and their influence on the pursuit of Massena; Wellington's passage of the Tagus, and his retreat from Burgos in 1812; the passage of the Adour and Garonne in 1814; and the failure of the mines to blow up the bridges of Saltador, Alcantara, &c.; but a sufficient number of examples, it is believed, has already been adduced to show the advantage of maintaining a properly organized and instructed body of sappers, miners, and pontoniers, and the fatal results attending the want of such troops, as a component part of an army organization.

It has already been remarked that the infantry of an army must always form the basis of the apportionment; and by the general rule laid down by military writers, the cavalry should be from one-fourth to one-sixth of the infantry, according to the character of the war; the artillery about two-thirds of the cavalry, or one-seventh of the infantry; and the engineers from one-half to three-fourths of the artillery,—say about two-thirds. The staff and administrative corps must vary according to the nature of the organization, and the character of the theatre of war. The former ought to be from two to five in a thousand, and the latter from twenty-five to seventy-five,[40] as a general rule. These ratios would give for a good army organization;

Staff, about ................................... 5 Administrative service—pay, medical, commissary, quarter-master, &c. .............................65 Infantry, ......................................650 Cavalry, .......................................130 Artillery, ......................................90 Engineers, ......................................60 ——- Total, ...................1,000

In a broken country, and against savage and undisciplined foes, like the Indians in this country, the natives opposed to the English in India, to the French in Algeria, or to the Russians in Circassia, the cavalry, artillery, and engineers would be diminished, and the infantry and administrative corps proportionably increased; the former because light troops are always preferable against an undisciplined foe, and the latter because of the difficulty of moving and procuring supplies in new and uncultivated countries. The French forces in Algeria, in 1844, amounted to about sixty thousand men, in the following proportion:—

Staff, ...................................4.7 Administrative, &c., ...................112.3 Infantry, ..............................687.3 Cavalry, ................................86.6 Artillery, ..............................61.2 Engineers, ..............................47.9 ————- 1000 men.

[Footnote 40: This supposes the teamsters, wagon-masters, hospital-servants, &c., to be enlisted men, and not persons hired for the occasion as is done in our army.]

In small peace establishments the relative proportion of infantry and cavalry should be much less than when prepared for the field, because troops for these two arms can be much more readily formed in case of emergency, than for those which require more scientific information, and technical skill and instruction. The staff and engineers are evidently the most difficult to be formed in case of war, and next to these the artillery and administrative corps.

In this country we can maintain, in time of peace, only the framework of an army, looking to our citizen soldiery to form, in case of need, the great mass of our military force. This is the starting point in our military system, and the basis of our army organization. Let us see whether this principle is carried out in practice.

For every thousand men in our present organization[41] we have,

For the staff, 2 Administrative, 20[42] Infantry, 513 Cavalry, 150 Artillery, 310 Engineers, 5 —— 1000

[Footnote 41: These numbers are the real rather than the nominal proportions, many of our officers being called staff, who properly belong to one of the other classes.]

[Footnote 42: Much of the administrative duty in our army is done by unenlisted men, or by soldiers detached from their companies. Where such is the case, the ratio of this branch of the service ought to be no higher than is represented above.]

We see from this table, that while our artillery is nearly six times as numerous as in ordinary armies, our staff is less by one-half, and our engineers not more than one-half what ought to be their proportion in a war establishment. To this excess of artillery over infantry and cavalry in our army in time of peace there is no objection, inasmuch as the latter could be more easily expanded in case of war than the artillery. But for a still stronger reason our staff and engineers should also be proportionally increased, instead of being vastly diminished, as is actually the case.

Experience in the first campaigns of the American Revolution strongly impressed on the mind of Washington the absolute necessity of forming a regular and systematic army organization. But so difficult was it to obtain properly instructed engineers, that he was obliged to seek his engineer officers in the ranks of foreign adventurers, and to make drafts from the other arms of service, and have them regularly instructed in the duties of engineer troops, and commanded by the officers of this corps. An order, in his own handwriting, giving the details of this temporary arrangement, is dated March 30th, 1779. Until men are enlisted for the purpose, companies of sappers and miners shall be formed by drafts from the line. "The duties of the companies of sappers and miners," he continues, "shall be under the direction of the engineers, to construct field-works of every kind, and all works necessary for the attack or defence of places, as circumstances may require. On a march in the vicinity of an enemy, a detachment of the companies of sappers and miners shall be stationed at the head of the column, directly after the vanguard, for the purpose of opening and mending the roads, and removing obstructions," &c. &c.

The great difficulties encountered by Washington in instructing his inexperienced forces in the more difficult branches of the art, made him the more earnest, in after years, to impress on us how important it was for us In peace to prepare for war. The preparation here meant is not the keeping up, in time of peace, of a large standing army, ever ready to take the field; but rather the formation of a small body, educated and practised in all the scientific and difficult parts of the profession; a body which shall serve as the cadre or framework of a large army, capable of imparting to the new and inexperienced soldiers of the republic that skill and efficiency which has been acquired by practice. How far have we accomplished this object, and what will be the probable operations in case of another contest with a European power? New and inexperienced troops will be called into the field to oppose a veteran and disciplined army. From these troops we shall expect all the bravery and energy resulting from ardent patriotism and an enthusiastic love of liberty. But we cannot here expect much discipline, military skill, or knowledge of the several branches of the military art. The peaceful habits of our citizens tend but little to the cultivation of the military character. How, then, are we to oppose the hostile force? Must human blood be substituted for skill and preparation, and dead bodies of our citizens serve as epaulements against the inroads of the enemy? To some extent, we fear it must be the case; but not entirely so, for government has not altogether neglected to make preparation for such an event. Fortifications have been planned or erected on the most important and exposed positions; military materials and munitions have been collected in the public arsenals; a military school has been organized to instruct in the military sciences; there are regularly kept up small bodies of infantry and cavalry, weak in numbers, but capable of soon making good soldiers of a population so well versed as ours is in the use of the musket and the horse; an artillery force, proportionally much larger, is also regularly maintained, with a sufficient number of men and officers to organize and make good artillery-men of citizens already partially acquainted with the use of the cannon. But an acquaintance with infantry, cavalry, and artillery duties is not the only practical knowledge requisite in war. In the practical operations of an army in the field, rivers are to be crossed, bridges suddenly erected and suddenly destroyed, fieldworks constructed and defended, batteries captured and destroyed; fortifications are to be put in order and defended, or to be besieged and recaptured; trenches must be opened, mines sprung, batteries established, breaches made and stormed; trous-de-loup, abattis, palisades, gabions, fascines, and numerous other military implements and machinery are to be constructed. Have our citizens a knowledge of these things, or have we provided in our military establishment for a body of men instructed and practised in this branch of the military art, and capable of imparting to an army the necessary efficiency for this service? Unfortunately this question must be answered in the negative; and it is greatly to be feared that the future historian will have to say of us, as Napier has said of the English:—"The best officers and soldiers were obliged to sacrifice themselves in a lamentable manner, to compensate for the negligence and incapacity of a government always ready to plunge the nation into a war, without the slightest care of what was necessary to obtain success. Their sieges were a succession of butcheries; because the commonest materials, and the means necessary to their art, were denied the engineers."[43]

[Footnote 43: The subjects discussed in this chapter are also treated by most authors on Military Organization and Military History, and by the several writers on Military Engineering. Allent, Vauban, Cormontaigne, Rocquancourt, Pasley, Douglas, Jones, Belmas, Napier, Gay de Vernon, may be referred to with advantage. Pasley, Douglas, Jones, and Napier, speak in the strongest terms of the importance of engineer troops in the active operations of a war, and of the absolute necessity of organizing this force in time of peace. A list of books of reference on Military Engineering will be given at the close of the following chapters.

While these pages are passing through the press, Congress has authorized the President to raise one company of engineer troops! This number is altogether too small to be of any use in time of war.]



CHAPTER XIII.

PERMANENT FORTIFICATIONS.

Fortification is defined,—the art of disposing the ground in such a manner as to enable a small number of troops to resist a larger army the longest time possible. If the work be placed in a position of much importance, and its materials be of a durable character, it is called permanent; if otherwise, it receives the appellation of field, or temporary. Fieldworks are properly confined to operations of a single campaign, and are used to strengthen positions which are to be occupied only for a short period. Generally these works are of earth, thrown up by the troops in a single day. They are intimately connected with a system of permanent fortifications, but from the facility of their construction, no provision need be made for them before the actual breaking out of war. Indeed, they could not well be built before hostilities commenced, as their locality in each case must be determined by the position of the hostile forces.

Having already described the general influence of permanent fortifications as a means of national defence, we shall here speak merely of the principles of their construction. It is not proposed to enter into any technical discussion of matters that especially belong to the instruction of the engineer, but merely to give the nomenclature and use of the more important parts of a military work; in a word, such general information as should belong to officers of every grade and corps of an army.

The first species of fortification among the ancients was of course very simple, consisting merely of an earthen mound, or palisades. A wall was afterwards used, and a ditch was then added to the wall. It was found that a straight wall could be easily breached by the enemy's battering-rams; to remedy this evil, towers were built at short intervals from each other, forming a broken line of salient and re-entering parts. These towers or salient points gradually assumed a shape approximating to the modern bastion.

After the invention of gunpowder and the application of cannon to the attack and defence of places, it became necessary to arrange earthen ramparts behind the thin walls of the ancient works, for the reception of the new artillery. Moreover these walls were soon found inadequate to resist the missiles of the besiegers, and it became necessary to replace them by parapets of earth. In order to cover the retaining walls of these parapets from the besieging batteries, it was also found to be necessary to lower these walls as much as possible, and to raise the counterscarps. The traces or plans of the works, however, received no material change till about the close of the fifteenth century.

It is not known who first changed the ancient towers into bastions. Some attribute it to an Italian, and with considerable show of reason, for a bastion was built at Turin as early as 1461. Achmet Pacha, it is said, fortified Otranto in this way, in 1480, but whether the system was previously known among the Turks cannot be determined. Others attribute the invention to Ziska, the celebrated leader of the Hussites. It is most probable that the transition from the tower to the bastion was a very gradual one, and that the change was perfected in several countries at about the same time.

Fortifications, like other arts and sciences, greatly flourished in Italy under the Medicis, and that country furnished Europe with its most skilful engineers. Catharine of Medicis introduced into France many of her countrymen, distinguished in this profession; among these may be named Bellamat, Bephano, Costritio, Relogio, Vorganno, the two Marini, Campi, and Hieronimo, who built several important places and directed the sieges of others. These able foreigners were rivalled by some distinguished French engineers, who laid the foundation of the "corps du Genie" which has since become a school of military instruction for the world. Among the early French engineers may be distinguished Lafontaine De Serre, Feuquieres, and St. Remy. Pedro Navarro had been appointed a member of this corps, but his attention was more specially directed to mining, and we do not learn that he distinguished himself in the construction of any fortification.

In Germany, in the beginning of the sixteenth century, Albert Durer distinguished himself as a writer on fortification; his book is remarkable as containing the germs of many of the improvements which were made by those who followed him. This is the more to be wondered at as he was not a professed engineer. After him followed Spekel, a native of Strasburg, who died in 1589. His writings are valuable as showing the state of the art at that time, and the changes which he himself introduced. He was an engineer of much practical knowledge and experience, having assisted at the sieges of Malta, Golletta, Vienna, Jula, Nicosia, Famagusta, &c.

The first French engineer who wrote on fortification was Errard de Bar-le-Duc, who published near the close of the sixteenth century. As an engineer, he was rivalled by Chatillon, a man of distinguished merit. Errard fortified Amiens, built a part of the castle of Sedan, and a portion of the defences of Calais. Under the reign of Louis XIII., Desnoyers, Deville, Pagan, and Fabre were greatly distinguished. Deville published in 1628. He was a man of much learning and experience; but he is said to have adopted, both in his theory and practice, the principles of the Italian school, with most of its errors. Pagan began his military career while young, and became marechal de champ at the age of 38, when, having the misfortune to become blind, he was compelled to relinquish his brilliant hopes. He was the ablest engineer of his age, and was also greatly distinguished in other branches of science. In his plans he inclined to the Dutch rather than the Italian school of fortification. He published in 1645.

At the close of the sixteenth century, the Dutch had been forced to resort to military defences to protect themselves against the aggressions of the Spaniards. As the Dutch were inferior in other military means, fortification became one of the vital resources of the country. Their works, however, thrown up in much haste, were in many respects defective, although well adapted to the exigencies of the time. Freytag, their principal engineer, wrote in 1630. Some of his improvements were introduced into France by Pagan. He was preceded by Marolois, (a cotemporary of Pagan,) who published in 1613.

In Germany, Rimpler, a Saxon, wrote on fortification in 1671. He was a man of great experience, having served at the sieges of Candia, Phillipsburg, Bonn, Riga, Bremen, Dansburg, Bommeln, &c. He fell at the siege of Vienna in 1683. His writings are said to contain the groundwork of Montalembert's system.

In Italy, after the time of Tartaglia, Marchi, Campi, &c., we find no great improvement in this art. Several Italians, however, distinguished themselves as engineers under the Spaniards. The fortifications of Badajos are a good example of the state of the art in Italy and Spain a that epoch. The citadel of Antwerp, built by two Italian engineers, Pacciotti and Cerbelloni, in 1568, has become celebrated for the siege it sustained in 1832.

The age of Louis XIV. effected a great revolution in the art of fortification, and carried it to such a degree of perfection, that it has since received but slight improvement. The years 1633 and 1634 are interesting dates in the history of this art, as having given birth respectively to Vauban and Coehorn. The former was chief engineer of France under Louis XIV., and the latter held a corresponding position under the Dutch republic. Coehorn's ideas upon fortification are conceived with an especial view to the marshy soil of his own country, and, although well suited to the object in view, are consequently of less general application than those of his more distinguished cotemporary and rival. The best specimens of his mode of construction that exist at the present day, are the fortresses of Manheim, Bergen-op-Zoom, Nimiguen, and Breda.

Coehorn was followed in Holland by Landsberg, an able and practical engineer, who to much reading added extensive experience, having himself served at sixteen sieges. His system was in many respects peculiar, both in trace and relief; it dispensed with the glacis, and all revertments of masonry. His plans could be applied only to marshy soils. The first edition of his work was published in 1685.

But the career of Vauban forms the most marked and prominent era in the history of fortification; it constitutes the connecting link between the rude sketches of the earlier engineers, and the well-established form which the art has since assumed. In his earlier works we find many of the errors of his predecessors; but a gradual change seems to have been wrought in his mind by reflection and experience, and these faults were soon remedied and a new and distinct system developed. Vauban has left no treatise upon his favorite art, and his ideas upon fortification have been deduced from his constructions, and from detached memoirs left among his papers. The nature of his labors, and the extent of his activity and industry, may be imagined from the fact that he fought one hundred and forty battles, conducted fifty-eight sieges, and built or repaired three hundred fortifications. His memoirs, found among his manuscript papers, on various military and political subjects, are numerous, and highly praised even at the present day. But his beautiful and numerous constructions, both of a civil and military character, are real monuments to his genius. The best illustrations of his principles of fortification occur at Lille, Strasbourg, Landau, Givet, and Neuf-Brisack. His writings on mines, and the attack and defence of places, are, by the profession, regarded as classic. His improvements in the existing method of attack gave great superiority to the arms of his countrymen, and even enabled him to besiege and capture his rival Coehorn, in his own works. He died in 1707, and was soon succeeded by Cormontaigne.

The latter did not attempt the introduction of any new system, but limited himself to improving and perfecting the plans of his illustrious predecessors. His improvements, however, were both extensive and judicious, and are sufficient to entitle him to the place he holds as one of the ablest military engineers the world has ever produced. His works on the subject of fortification, besides being elegantly written, contain the most valuable information of any works we have. His most admired constructions are to be found at Metz, Thionville, and Bitche. The beautiful crown works of Billecroix, at Metz, are perfect models of their kind. Cormontaigne died in 1750.

Cotemporary with him were Sturin and Glasser. The former deviated but slightly from the systems of his predecessors, but the latter invented several ingenious improvements which gave him great reputation.

Next follows Rosard, a Bavarian engineer; and Frederick Augustus, king of Poland, who devoted himself particularly to this art. The former casemated only the flanks of his works, but the latter introduced casemate fire more extensively than any one who had preceded him.

In France, Belidor and De Filey published about the middle of the last century. They were both able engineers but their systems were inferior to that of Cormontaigne.

In 1767 De la Chiche introduced a system of fortification in many respects original. He raised his covered-ways so as to conceal all his masonry, and casemated a great portion of his enceinte. For exterior defence, he employed direct fire from his barbettes, and curvated fire from his casemates; the direct fire of the latter secured his ditches.

Next to De la Chiche follows Montalembert, who published in 1776. He was a man of much experience and considerable originality, but of no great ability as an engineer. Most of his ideas were derived from De la Chiche and the German school of Rimpler. His plans have generally been rejected by his own countrymen, but they still have advocates among the Germans.

General Virgin, a distinguished Swedish engineer, wrote in 1781. His idea of strongly fortifying the smaller towns to the comparative neglect of the larger cities, constitutes one of the principal novelties in his system.

In 1794, Reveroni devised a system in which the casemates of Montalembert were employed, but his guns were so arranged as to be employed in barbette while the besiegers were at a distance, and afterwards to be used for casemated fire. The casemate gun-carriage, which formed a part of his invention, was ingenious, but never much employed in practice.

Bousmard, a French emigrant, published in 1790. He adopted the general trace of Vauban, but introduced modifications in the details essentially different from those of Cormontaigne. Some of these modifications are very valuable improvements, while others are of a more doubtful character. Bousmard is, on the whole, a very able writer, and his works should be found in the library of every military engineer.

Carnot's celebrated treatise was published in 1810. He was evidently a man of genius, and during his career at the head of the War Department of France, numerous and very important improvements were made in the several branches of the military art, and especially in strategy. His work on fortification exhibits much originality and genius, but it is doubtful whether it has very much contributed to the improvement of this art. His ideas have been very severely, and rather unfairly criticised by the English, and particularly by Sir Howard Douglas.

Chasseloup de Laubat early distinguished himself as an engineer of much capacity and talent. He followed Napoleon in nearly all his campaigns, and conducted many of his sieges. He remodelled the fortifications of Northern Italy and of the Lower Rhine. He published in 1811. The improvements which he introduced are numerous and valuable, and he probably contributed more to advance his art, and to restore the equilibrium between attack and defence, than any other engineer since Cormontaigne. After the fall of Napoleon and the partition of his empire, the allies mutilated or destroyed the constructions of Chasseloup, so that, it is believed, no perfect specimen of his system remains.

The cotemporaries of Chasseloup were mostly engaged in active field service and sieges, and few had either leisure or opportunity to devote themselves to improvements in permanent fortification.

Choumara published in 1827. His system contains much originality, and his writings give proof of talent and genius. He has very evidently more originality than judgment, and it is hardly probable that his system will ever be generally adopted in practice.

The Metz system, as arranged by Noizet, as a theoretical study, is undoubtedly the very best that is now known. It, however, requires great modifications to suit it to different localities. For a horizontal site, it is probably the most perfect system ever devised. It is based on the system of Vauban as improved by Cormontaigne, and contains several of the modifications suggested by modern engineers. It is applied in a modified form to the new fortifications of Paris.

Baron Rohault de Fleury has introduced many modifications of the ordinary French system in his new defences of Lyons. We have seen no written account of these works, but from a hasty examination in 1844, they struck us as being too complicated and expensive.

The new fortifications of Western Germany are modifications of Rempler's system, as improved by De la Chiche and Montalembert. It is said that General Aster, the directing engineer, has also introduced some of the leading principles of Chasseloup and Carnot.

The English engineers have satisfied themselves with following in the track of their continental neighbors, and can offer no claims to originality.

Of the system of fortification now followed in our service we must decline expressing any opinion; the time has not yet arrived for subjecting it to a severe and judicious criticism. But of the system pursued previous to 1820, we may say, without much fear of contradiction, that a worse one could scarcely have been devised. Instead of men of talent and attainments in military science, most of our engineers were then either foreigners, or civilians who owed their commissions to mere political influence. The qualifications of the former were probably limited to their recollection of some casual visit to two or three of the old European fortresses; and the latter probably derived all their military science from some old military book, which, having become useless in Europe, had found its way into this country, and which they had read without understanding, and probably without even looking at its date. The result was what might have been anticipated—a total waste of the public money. We might illustrate this by numerous examples. A single one, however, must suffice. About the period of the last war, eight new forts were constructed for the defence of New York harbor, at an expense of some two millions of dollars. Six of these were circular, and the other two were star forts—systems which had been discarded in Europe for nearly two thousand years! Three of these works are now entirely abandoned, two others are useless, and large sums of money have recently been expended on the other three in an attempt to remedy their faults, and render them susceptible of a good defence. Moreover, a number of the works which were constructed by our engineers before that corps was made to feel the influence of the scientific education introduced through the medium of the Military Academy—we say, a considerable number of our fortifications, constructed by engineers who owed their appointment to political influence, are not only wrong in their plans, but have been made of such wretched materials and workmanship that they are already crumbling into ruins.

A fortification, in its most simple form, consists of a mound of earth, termed, the rampart, which encloses the space fortified; a parapet, surmounting the rampart and covering the men and guns from the enemy's projectiles; a scarp wall, which sustains the pressure of the earth of the rampart and parapet, and presents an insurmountable obstacle to an assault by storm; a wide and deep ditch, which prevents the enemy from approaching near the body of the place; a counterscarp wall, which sustains the earth on the exterior of the ditch; a covered way, which occupies the space between the counterscarp and a mound of earth called a glacis, thrown up a few yards in front of the ditch for the purpose of covering the scarp of the main work.

The work by which the space fortified is immediately enveloped, is called the enceinte, or body of the place. Other works are usually added to the enceinte to strengthen the weak points of the fortification, or to lengthen the siege by forcing the enemy to gain possession of them before he can breach the body of the place: these are termed outworks, when enveloped by the covered way, and advanced works, when placed exterior to the covered way, but in some way connected with the main work; but if entirely beyond the glacis, and not within supporting distance of the fortress, they are called detached works.

In a bastioned front the principal outwork is the demi-lune, which is placed in front of the curtain; it serves to cover the main entrance to the work, and to place the adjacent bastions in strong re-enterings.

The tenaille is a small low work placed in the ditch, to cover the scarp wall of the curtain and flanks from the fire of the besieger's batteries erected along the crest of the glacis.

The places of arms, are points where troops are assembled in order to act on the exterior of the work. The re-entering places of arms, are small redans arranged at the points of junction of the covered ways of the bastion and demi-lune. The salient places of arms are the parts of the covered way in front of the salients of the bastion and demi-lune.

Small permanent works, termed redoubts, are placed within the demi-lune and re-entering places of arms for strengthening those works. Works of this character constructed within the bastion are termed interior retrenchments; when sufficiently elevated to command the exterior ground, they are called cavaliers.

Caponniers are works constructed to cover the passage of the ditch from the tenaille to the gorge of the demi-lune, and also from the demi-lune to the covered way, by which communication may be maintained between the enceinte and outworks.

Posterns are underground communications made through the body of the place or some of the outworks.

Sortie-passages are narrow openings made through the crest of the glacis, which usually rise in the form of a ramp from the covered way, by means of which communication may be kept up with the exterior. These passages are so arranged that they cannot be swept by the fire of the enemy. The other communications above ground are called ramps, stairs, &c.

Traverses are small works erected on the covered way to intercept the fire of the besieger's batteries.

Scarp and counterscarp galleries are sometimes constructed for the defence of the ditch. They are arranged with loop-holes, through which the troops of the garrison fire on the besiegers when they have entered the ditch, without being themselves exposed to the batteries of the enemy.

In sea-coast defences, and sometimes in a land front for the defence of the ditch, embrasures are made in the scarp wall for the fire of artillery; the whole being protected from shells by a bomb-proof covering over head: this arrangement is termed a casemate.

Sometimes double ramparts and parapets are formed, so that the interior one shall fire over the more advanced; the latter in this case is called a faussebraie.

If the inner work be separated from the other it is called a retrenchment[44] and if in addition it has a commanding fire, it is termed, as was just remarked, a cavalier.

[Footnote 44: The term retrenchment implies an interior work, which is constructed within or in rear of another, for the purpose of strengthening it; the term intrenchment, on the contrary, implies an independent work, constructed in the open field, without reference to any other adjoining work.]

The capital of a bastion is a line bisecting its salient angle. All the works comprehended between the capitals of two adjacent bastions is termed a front: it is taken as the unit in permanent fortification.

Fig. 39 represents the ground plan of a modern bastioned front, of a regular and simple form, on a horizontal site.

A, A, A—Is the enceinte, or body of the place. B—The bastions. C—The main ditch. D—The covered ways. E—The re-entering places of arms. F—The salient places of arms. G—The demi-lune. H—The demi-lune ditch. J—The demi-lune redoubt. L—The ditch of the demi-lune redoubt. M—The redoubt of the re-entering places of arms. N—The ditches of the redoubts. O—The tenaille. P—The double caponier. a—The traverses. b—The sortie-passages. c—Stairs. d—Cut in the demi-lune to flank the redoubt of the re-entering place of arms.

Fig. 40 represents a section through the line mn' of the preceding figure.

A—Is the rampart. B—The parapet. C—The ditch. D—The scarp wall. E—The counterscarp wall. F—The glacis. G—The covered way. H—The terre-plain. J—The parade.

Sometimes half embrasures are cut in the earthen parapet of a fort, so as to sink the gun below the crest, and thus more effectually cover the men from the enemy's fire.

But guns in embrasure have a far less extended field of fire than when mounted in barbette; moreover, the embrasures present openings through which an enemy may penetrate in an assault. Owing to these objections, they are employed only for the protection of particular points; that is, where it is important to cover the artillerists from the enemy's fire, or where the guns are to be used merely to protect a ditch, or to enfilade a road, &c. The bottom of the embrasure is called the sole, the sides are called cheeks, and the mass of earth between two embrasures, the merlon. Embrasures may be made either direct or oblique, according as the fire is required to be perpendicular or oblique to the parapet.

A coverport is a small outwork of any convenient form, erected immediately in front of a gateway, to screen it from the enemy's fire.

A counterguard is a more extensive work, constructed in front of a part of the fortress itself, or of some other outwork of greater importance, which it is intended to cover. These are sometimes called coverfaces, from their situation and object; but the former term is most commonly used.

Sometimes outworks, called tenaillons, consisting of one long and one short face, are placed on each side of the demi-lune of a front of fortification, for the purpose of prolonging the siege. (Fig. 41.)

Small, or demi-tenaillons, are frequently so arranged as to cover only one-half of the demi-lune, and then a bonnet constructed in front of the salient of the demi-lune. (Fig.42.) In this case the bonnet is flanked by the short faces of the demi-tenaillons; these short faces are themselves flanked by the demi-lune, while the bastions flank the long faces.

A horn-work consists of a front of fortification, and two wings resting on the faces of bastions of a front of the fortress. It sometimes has also a demi-lune or bonnet, as in the case of demi-tenaillons. (Fig. 43.)

A crown-work consists of two fronts of fortification, and two wings. (Fig. 44.) It is sometimes made double, and even triple.

These works are also employed as advanced works, and placed entirely in front of the glacis. They have generally been added to a fortress for the purpose of occupying some important piece of ground not included within the limits of the main work. They may be constructed with covered ways, and sometimes it may be found advantageous to secure them by retrenchments.

A detached work may be made in any form deemed best suited to the site. Being but remotely connected with the fortress, the latter will exercise but slight influence on the character of its plan or construction. They are usually of limited extent and slight relief, partaking much of the nature of field-works.[45]

[Footnote 45: The general principles of permanent fortification may be best learned from the writings of Cormontaigne, St. Paul de Noizet, and Laurillard-Fallot. A list of valuable books of reference on the several branches of military engineering will be given at the close of the next chapter.]



CHAPTER XIV.

FIELD-ENGINEERING.

Field-Engineering includes the making of military reconnaissances, temporary fortifications, and military roads; the planning and construction of military bridges; the attack and defence of military works;—in fine, all the various duties of engineer troops, either in the operations of a campaign, or in the dispositions on the battle-field.

Military reconnaissance.—By this term is meant an examination of a portion of the theatre of war, to ascertain its military character and resources. If the examination be made of a large district of country, and for an entire campaign, the reconnaissance is general; if made for collecting detailed information respecting a proposed line of march, the passage of a river, the position of an enemy, &c., it is termed special.

In making a general reconnaissance, great care should be taken to collect accurate information respecting the general topography of the country; the character of the mountains, forests, and water-courses; the nature of the roads, canals, and railways; the quality of the soil, and the amount of provisions and forage it produces; the population and character of the cities, towns, and villages, the commercial and manufacturing resources of every part of the country, and the means of transportation to be found in each district. The plan of military operations will be based on the information thus obtained, and any serious error in the reconnaissance may involve the results of the campaign, and even the fate of the war.

In a special reconnaissance, not only accurate but minute information will be required: the character of the roads must be given in detail; the nature of the water-courses, their depth and velocity; the position and character of bridges, and fords;—in fine, a full description of all obstacles to be encountered, and the means that can be made available for overcoming these obstacles.

A reconnoitring officer may usually derive much valuable information from the published maps and descriptions of the country to be examined; additional matters of detail may be obtained from woodsmen, hunters, and fishermen; and also from the innkeepers and local authorities of the district. But the officer should always verify this information, so far as practical, by personal examination. In making a reconnaissance in the vicinity of an enemy, he must be supported by a strong escort of mounted troops, and in all his operations the greatest precaution will be requisite to ensure success.

Some simple instrument, such as a pocket sextant, or compass, will be sufficient to enable the reconnoitring officer to measure, with considerable accuracy, the height of mountains, the width of streams, &c., and an ordinary scale and dividers will enable him to make a suitable military sketch.

Temporary Fortification.—It has been stated in the preceding chapter that temporary fortifications are properly confined to the operations of a single campaign, and are used to strengthen positions which are to be occupied only for a short period; and that they are usually made of earth, thrown up by the troops in a single day. Temporary fortifications, as a part of field-engineering, may therefore be regarded rather as an arm than an art. The principles of their construction are derived, of course, from the theory of permanent fortification, but in applying these principles to practice in the field, much greater latitude is allowed than in the exact scientific arrangement of permanent works.

The purpose of field-works (or intrenchments, as they are commonly called) is to arrest, or at least to impede, the march of the attacking foe; to shelter the defensive troops from the missive weapons of the assailants, and to detain them in a position where they will be exposed to the fire of the defensive force. The numerical and positive strength of the assailed may be much less than that of the assailant, and yet an equilibrium exist; the material obstacles compensating for the difference in numbers. Intrenchments, though inert masses, must therefore be regarded as most valuable and important accessaries in the defence of a position.

Intrenchments consist either of lines of works made to cover extended positions, or of detached works designed simply to defend the ground they occupy. The former generally present a front against the enemy in but one direction, while the latter are usually closed on all their sides.

The following figures have been employed for the plan of simple intrenchments, viz.: the polygon, redan, lunette, mitre, star-fort, and bastion.

Square or polygonal redoubts are the most common forms given to field-works, on account of the ease of their construction. But they have many defects. There is a sector without fire in front of each salient, and the ditches are without protection. The latter objection also holds good against all circular works.

The redan (Fig. 45) is frequently used to cover a point in rear, as a bridge, a ford, or a defile. When used alone, its gorge should be closed by palisades. Its ditches are unprotected.

The lunette (Fig. 46) has nearly the same defects as the redan.

The mitre, or priest-cap, (Fig. 47,) may be employed with advantage when a cross-fire is required on the capital of the work. The star-fort has all the defects, without the merit of simplicity, which belong to the polygonal redoubt.

The bastion-fort (Fig. 48) more fully satisfies the conditions of a good defence than any other plan; but it is less simple and easy of execution. It is usually composed of four or five fronts, but it may be applied to a polygon of any number of sides.

For the details of the construction of these several works, we must refer to the special treatises on field-fortification.

Lines of intrenchments may be made either continuous or with intervals. In adopting either plan, the engineer should avail himself of all the natural obstacles presented by the position, so as to diminish the labor of erecting artificial means of defence.

The simplest arrangement for a continuous intrenchment is the cremailliere or indented line. When applied to an irregular site, or used to connect together distant and detached works, the indented line may be regarded as a good disposition. Mitres and redans, connected by straight curtains, are sometimes employed, as also a combination of large and small redans, forming alternate salient and re-entering angles. A continuous line of bastions is preferable to any other arrangement, when there is plenty of time for their construction.

Lines with intervals are frequently formed of alternate lunettes and square redoubts. Other detached works may be employed in the same way. This manner of intrenching a position has several advantages, with disciplined troops. The first shock of the assailant is sustained by the detached works, and when he attempts to penetrate in the intervals, his flanks become exposed to a deadly cross fire. These intervals also allow the assailed to act on the offensive, by charging the enemy at the opportune moment. But with raw and militia forces it will be safer to resort to continuous lines. If cavalry form any part of the defensive force, it will be absolutely necessary to leave intervals through which these troops may charge.

A vertical section of all intrenchments is of the same general form; the dimensions will, of course, vary with the nature of the soil, and the time and means employed in their construction. The minimum dimensions that can be used with any considerable advantage are given in Fig. 49.

In laying out field-works advantage should be taken of all available artificial obstacles, such as hedges, walls, houses, outbuildings, &c. A thickset hedge may be rendered defensible by throwing up against it a slight parapet of earth. Stone fences may be employed in the same way. Walls of masonry may be pierced with loop-holes and arranged for one or two tiers of fire. The walls of houses are pierced in the same manner, and a projecting wooden structure, termed a machicoulis gallery, is sometimes made from the floor of the second story, to enable the assailed to fire down upon their opponents. This arrangement is frequently employed to advantage in wooden blockhouses against a savage foe; but it is of little avail when exposed to the fire of artillery. Some have proposed galleries of this description in permanent works of masonry, but the project is too obviously absurd to merit discussion.

In addition to the parapet of an intrenchment, a good engineer will always find time and means for constructing other artificial obstacles, such as trous-de-loup, abattis, palisades, stockades, fraises, chevaux-de-frise, crows'-feet, mines, &c.

Trous-de-loup are pits dug in the earth in the form of an inverted truncated cone, some six feet in diameter, and about the same number of feet in depth. They are usually placed a few yards in front of the ditch, and concealed by some slight covering.

Abattis are tops and large limbs of trees arranged along the glacis of a work; the ends of the branches are lopped off and sharpened.

Palisades are stakes some eight or ten feet long, with one end fastened in the ground and the other made sharp. They are placed in juxtaposition and connected together by horizontal riband-pieces. This arrangement is frequently placed at the foot of the counterscarp. When the timbers are large and the work is intended as a part of a primary defence, it is called a stockade; when the stakes are placed at the foot of the scarp, either horizontally or inclined, they receive the name of fraises.

A cheval-de-frise consists of a horizontal piece of timber armed with wooden or iron lances, which project some eight or ten feet. It is much employed against cavalry, and on rocky soils serves as a substitute for palisades.

Crows'-feet are small wooden or iron forms filled with sharp spikes. They are thrown, with their points upward, on ground which is to be passed over by cavalry.

Mines are sometimes used in connection with intrenchments, but more commonly in the attack and defence of permanent works. They will be noticed further on.

Fieldworks which are to be occupied for a considerable length of time will usually have their steeper slopes revetted, and be arranged with scarp and counterscarp, galleries, traverses, blindages, &c. Such works hold an intermediary rank between temporary and permanent fortification.

As examples of the importance of field fortifications and of the manner of organizing them, the reader is referred to the celebrated battle of Fontenoy, in 1745, where the carefully-arranged intrenchments of Marshal Saxe enabled the French to repel, with immense destruction, the attacks of greatly superior numbers; to the battle of Fleurus, in 1690, where the Prince of Waldeck exposed himself to a most disastrous defeat "by neglecting the resources of fortification and other indispensable precautions;" to the battle of Malplaquet, in 1709, where Marshal Villars, by neglecting to occupy and intrench the farm that closed the passage between the woods of Sars and Laniere, exposed himself to a disastrous defeat; to the operations of 1792, where General Custine, by neglecting to intrench the heights that covered Bingen, as the engineers had recommended, exposed himself to those terrible disasters which forced him to a precipitate retreat; to the works of Wervike, which, by a vigorous resistance on the 10th of September, 1793, saved the Dutch army from total destruction; to the intrenched camp of Ulm, in 1800, which for six weeks held in check the victorious army of Moreau; to the intrenched lines of Torres Vedras, in 1810, which saved from destruction the English army of Wellington; to the field-defences of Hougomont, which contributed so much to the victory of Waterloo, &c.

Military communications.—The movements of armies are always much embarrassed by forests, marshes, and water-courses, and nothing contributes more to the dispatch of military operations than the means of opening practical and easy communication through these various obstacles.

It is not necessary here to enter into any detailed discussion of the manner of constructing military communications through forests or marshes. In a new country like ours, where almost every one has had some experience in road-making, no very great technical knowledge is required for the construction of temporary works of this character; but much professional skill and experience will be requisite for the engineers who make the preliminary reconnaissances, and fix the location of these roads.

Water-courses may be crossed by means of fords, on the ice, or by ferries and bridges. When temporary bridges or ferries are constructed by the army in the field, they are classed under the general head of military bridges, or more properly, pontoniering.

Where the depth of the stream is not great, the current slight, and the bottom smooth and hard, the passage may be effected by fording. If the bottom be of mud, or large stones, the passage will be difficult and dangerous, even where the depth and current are favorable. Under favorable circumstances infantry can ford a stream where the depth is not greater than four feet; cavalry to a depth of four or five feet; but artillery, and engineer trains, cannot go to a depth of more than two and a half feet, without greatly exposing their ammunition and military stores The fords should be accurately staked out before the passage is attempted, and ropes ought to be stretched across the stream, or cavalry and small boats stationed below, to prevent the loss of life.

Ice may be crossed by infantry, in small detachments. Its strength may be increased by covering it with boards, or straw, so as to distribute the weight over a greater surface. By sprinkling water over the straw, and allowing it to freeze, the mass may be made still more compact. But large bodies of cavalry, and heavy artillery, cannot venture on the ice unless it be of great thickness and strength. An army can never trust, for any length of time, to either fords or ice; if it did a freshet or a thaw would place it in a most critical state. Military bridges will, therefore, become its only safe reliance for keeping open its communications.

Military bridges are made with trestles, rafts, boats, and other floating bodies. Rope bridges are also sometimes resorted to by troops for passing rivers.

Trestle bridges are principally used for crossing small streams not more than seven or eight feet in depth: they also serve to connect floating bridges with the shore, in shallow water. The form of the trestle is much the same as that of an ordinary carpenter's horse, i.e., a horizontal beam supported by four inclined legs. These trestles are placed in the stream, from twelve to twenty feet apart, and connected by string-pieces, (or balks as they are termed in technical language,) which are covered over with plank. The action of the current against the bridge may be counteracted by anchors and cables, or by means of boxes or baskets attached to the legs of the trestles, and filled with stones. A more substantial form may be given to the bridge by substituting for the trestles, piles, or the ordinary framed supports so much used in the newer parts of our country.

For examples of the use of bridges of this description we would refer to Caesar's celebrated bridge across the Rhine; the passage of the Scheldt in 1588 by the Spaniards; the passage of the Lech in 1631 by Gustavus Adolphus; the passage of the Danube in 1740 by Marshal Saxe; the great bridge across the Var during Napoleon's Italian campaigns; the passage of the Lech in 1800 by Lecourbe; the bridges across the Piava, the Isonso, &c., in the subsequent operations of the army in Italy; the celebrated passage of the Danube at the island of Lobau in 1809; the passage of the Agueda in 1811 by the English; the passages of the Dwina, the Moscowa, the Dneiper, the Beresina, &c., in the campaign of 1812; the repairing of the bridge near Dresden, and the passage of the Elbe in 1813, &c.

Rafts formed of timbers, casks, barrels, &c., are frequently used as military bridges. They may be made to bear almost any weight, and will answer for the passage of rivers of any depth and width, provided the current be not rapid.