always have another farther to the rear to fall back into.

To provision an army, campaigning against so formidable a foe through
such a country, from wagons alone seemed almost impossible. System and
discipline were both essential to its accomplishment.

The Union armies were now divided into nineteen departments, though four
of them in the West had been concentrated into a single military
division. The Army of the Potomac was a separate command and had no
territorial limits. There were thus seventeen distinct commanders.
Before this time these various armies had acted separately and
independently of each other, giving the enemy an opportunity often of
depleting one command, not pressed, to reinforce another more actively
engaged. I determined to stop this. To this end I regarded the Army of
the Potomac as the centre, and all west to Memphis along the line
described as our position at the time, and north of it, the right wing;
the Army of the James, under General Butler, as the left wing, and all
the troops south, as a force in rear of the enemy. Some of these latter
were occupying positions from which they could not render service
proportionate to their numerical strength. All such were depleted to
the minimum necessary to hold their positions as a guard against
blockade runners; where they could not do this their positions were
abandoned altogether. In this way ten thousand men were added to the
Army of the James from South Carolina alone, with General Gillmore in
command. It was not contemplated that General Gillmore should leave his
department; but as most of his troops were taken, presumably for active
service, he asked to accompany them and was permitted to do so.
Officers and soldiers on furlough, of whom there were many thousands,
were ordered to their proper commands; concentration was the order of
the day, and to have it accomplished in time to advance at the earliest
moment the roads would permit was the problem.

As a reinforcement to the Army of the Potomac, or to act in support of
it, the 9th army corps, over twenty thousand strong, under General
Burnside, had been rendezvoused at Annapolis, Maryland. This was an
admirable position for such a reinforcement. The corps could be brought
at the last moment as a reinforcement to the Army of the Potomac, or it
could be thrown on the sea-coast, south of Norfolk, in Virginia or North
Carolina, to operate against Richmond from that direction. In fact