The engineers, in modern army organization, constitute the fourth arm of service, as, compared with artillery, their relative numbers are about as two to three. They are divided in the same manner as the artillery, viz.:—1st, the staff; 2d, guards, or fort-keepers; 3d, artificers; and 4th, the troops.
I. The officers constituting the staff of this corps are charged in time of peace with planning, constructing, and repairing all fortifications and other defensive works; the construction and preparation of all military materials, and stores connected with this arm; and (in our service) with the disbursements of money connected with these operations: in time of war they are charged with the attack and defence of military works, the laying out and construction of field defences, redoubts, intrenchments, roads, &c.; in the attack they form a part of the vanguard, to remove obstructions; and in retreat they form a part of the rear-guard, to erect obstacles, destroy roads, bridges, &c., so as to retard an enemy's pursuit.
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 dépôts 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 field-works.