The engineers’ special duties were to make roads passable for the army by corduroying sloughs, building trestle bridges across small streams, laying pontoon bridges over rivers, and taking up the same, laying out and building fortifications, and slashing. Corduroying called at times for a large amount of labor, for Virginia mud was such a foe to rapid transit that miles upon miles of this sort of road had to be laid to keep ready communication between different portions of the army. Where the ground was miry, two stringers were laid longitudinally of the road, and on these the corduroy of logs, averaging, perhaps, four inches in diameter, was laid, and a cover of brush was sometimes spread upon it to prevent mules from thrusting their legs through. Where the surface was simply muddy, no stringers were used. It should be said here that by far the greater portion of this variety of work fell to fatigue details from the infantry, as did much more of the labor which came within the scope of the engineers’ duties; for the latter could not have accomplished one-fifth of the tasks devolved upon them in time. In fact, if I except the laying and taking-up of pontoon bridges, and the laying-out and superintending of the building of forts, there were none of the engineers’ duties which were not performed by the fighting force to a large extent. I state this not in detraction of the engineers, who always did well, but in justice to the infantry, who so often supplemented the many and trying duties of their own department with the accomplishments of the engineer corps. The quartermaster of the army had a large number of wagons loaded with intrenching tools with which to supply the troops when their services were required as engineers.
A TRESTLE BRIDGE, NO. 1.
The building of trestle bridges called for much labor from the engineers with the Army of the Potomac, for Virginia is gridironed with small streams. These, bear in mind, the troops could ford easily, but the heavily loaded trains must have bridges to cross on, or each ford would soon have been choked with mired teams. Sometimes the bridges built by the natives were still standing, but they had originally been put up for local travel only, not to endure the tramp and rack of moving armies and their thousands of tons of impedimenta; wherefore the engineers would take them in hand and strengthen them to the point of present efficiency. So well was much of this work done that it endures in places to-day as a monument to their thoroughness and fidelity, and a convenience to the natives of those sections.
A TRESTLE BRIDGE, NO. 2.
When a line of works was laid out through woods, much slashing, or felling of trees, was necessary in its front. This was especially necessary in front of forts and batteries. Much of this labor was done by the engineers. The trees were felled with their tops toward the enemy, leaving stumps about three feet high. The territory covered by these fallen trees was called the Slashes, hence Slashing. No large body of the enemy could safely attempt a passage through such an obstacle. It was a strong defence for a weak line of works.
The Gabions, being hollow cylinders of wicker-work without bottom, filled with earth, and placed on the earthworks; the Fascines, being bundles of small sticks bound at both ends and intermediate points, to aid in raising batteries, filling ditches, etc.; Chevaux-de-frise, a piece of timber traversed with wooden spikes, used especially as a defence against cavalry; the Abatis, a row of the large branches of trees, sharpened and laid close together, points outward, with the butts pinned to the ground; the Fraise, a defence of pointed sticks, fastened into the ground at such an incline as to bring the points breast-high;—all these were fashioned by the engineer corps, in vast numbers, when the army was besieging Petersburg in 1864.
A LARGE GABION.