g of many battle fields
where fought and fell brave troopers from every Northern State.

The chief duties of officers belonging to the _corps of engineers_, when
connected with an army acting in the field, are the supervision of
routes of communication, the laying of bridges, the selection of
positions for fortifications, and the indication of the proper character
of works to be constructed. Should a siege occur, a new and very
important class of duties devolves on them, relating to the trenches,
saps, batteries, etc.

Not only is there in Virginia a lack of good roads, but the numerous
streams have few or no bridges. In many cases where bridges have
existed, one or the other of the contending armies has destroyed them to
impede the march of its opponents. Streams which have an average depth
of three or four feet are, however, generally without bridges, except
where crossed by some turnpike, the common country roads mostly leading
to fords. The famous Bull Run is an example. There were but two or three
bridges over this stream in the space of country penetrated by the roads
generally pursued by our army in advancing or retreating, and these have
been several times destroyed and rebuilt. The stream varies from two to
six feet in depth--the fords being at places of favorable depth, and
where the bottom is gravelly and the banks sloping. Often such streams
as this, and indeed smaller ones, become immensely swelled in volume by
storms, so that a comparatively insignificant rivulet might greatly
delay the march of an army, if means for quickly crossing should not be
provided. The general depth of a ford which a large force, with its
appurtenances, can safely cross, is about three feet, and even then the
bottom should be good and the current gentle. With a greater depth of
water, the men are likely to wet their cartridge boxes, or be swept off
their feet. There is a small stream about three miles from Alexandria,
crossing the Little River turnpike, which has never been bridged, and
which was once so suddenly swollen by rain that all the artillery and
wagons of a corps were obliged to wait about twelve hours for its
subsidence. The mules of some wagons driven into it were swept away.
Fords, unless of the best bottom, are rendered impassable after a small
portion of the wagons and artillery of an army have crossed them--the
gravel being cut through into the underlying clay, and the banks
converted into sloughs by the dripping