Revised United States Army regulations of 1861, with an appendix containing the changed and laws affecting Army regulations and Articles of war to June 25, 1863:

F0 R THIE ARMY. 109
Convoys and their Escorts.
758. The advance guard precedes the convoy far enough to remove all
obstacles to its advance. It examines the woods, defiles, and villages.
and by mounted men gives information to the commander, and receives
his orders. It reconnoitres places for halts and parks.
759. If the head of the column is threatened, the advanced guard
seizes the defiles and places which the enemy might occupy, and holds
them until the main body advances to the front and relieves it; the main
body holds the positions until the head of the convoy arrives, and then
leaves detachments which are relieved by the parties marching with the
divisions; the posts are not abandoned until the whole convoy has passed
and the position is no longer important.
760. When the rear is threatened, like measures are taken; the rear
guard defends the ground and retards the enemy by breaking the bridges
and blocking the road.
761. If the flanks are threatened, and the ground is broken, and many
defiles are to be passed, the defense of the convoy becomes more difficult;
the advance and rear guards must be reduced, the flanks strengthened, and
positions which will cover the march of the convoy must be occupied by
the main body of the troops before the head of the convoy reaches them,
and until it has passed.
762. If the convoy is large, and has to pass places that the force and
position of the enemy make dangerous, the loss of the whole convoy must
not be risked; it must pass by divisions, which reunite after the passage.
In this case the greater part of the troops guard the first division; they
seize the important points, and cover them with light troops, or, if necessary, with small posts, and hold them until all the divisions have passed.
763. If there is artillery in the convoy, the commander of the escort
uses it for the defense.
764. To move faster and make the defense easivr, the wagons move in
double file whenever the road allows it. If a wagon breaks, it is at once
removed from the road; when repaired, it takes the rear; when it cannot
be repaired, its load and horses are distributed to some of the other
wagons kept in the rear for that purpose.
765. Convoys by water are escorted on the same principles. Each
boat has a small infantry guard; one portion of the escort precedes or
follows the convoy in boats. The cavalry march opposite the convoy;
the advance and rear guard move by land, and a]' are connected by flankers with the convoy. Where a river runs through a narrow valley, the
body of the infantry moves by land to prevent the enemy from occupying
the heights and disturbing the cornvoy.
766. Convoys halt every hour to let the horses take bre.::t and the
wagons o)e up. Long hakt are may but seldom, anA only in places
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