If North and South Carolina were rendered helpless so far as capacity for feeding Lee's army was concerned, the Confederate garrison at Richmond would be reduced in territory, from which to draw supplies, to very narrow limits in the State of Virginia; and, although that section of the country was fertile, it was already well exhausted of both forage and food.

I approved Sherman's suggestion therefore at once.
The work of preparation was tedious, because supplies, to load the wagons for the march, had to be brought from a long distance.

Sherman would now have to march through a country furnishing fewer provisions than that he had previously been operating in during his march to the sea.

Besides, he was confronting, or marching toward, a force of the enemy vastly superior to any his troops had encountered on their previous march; and the territory through which he had to pass had now become of such vast importance to the very existence of the Confederate army, that the most desperate efforts were to be expected in order to save it.
Sherman, therefore, while collecting the necessary supplies to start with, made arrangements with Admiral Dahlgren, who commanded that part of the navy on the South Carolina and Georgia coast, and General Foster, commanding the troops, to take positions, and hold a few points on the sea coast, which he (Sherman) designated, in the neighborhood of Charleston.
This provision was made to enable him to fall back upon the sea coast, in case he should encounter a force sufficient to stop his onward progress.

He also wrote me a letter, making suggestions as to what he would like to have done in support of his movement farther north.