Adm. Porter’s gunboats could be a useful tool in supporting our land forces as we attempt to defend ourselves from a possible attack from Gen. Johnston’s army of relief. I wrote him,
NEAR Vicksburg, MISS., May 29, 1863.
Rear-Admiral DAVID D. PORTER, Comdg. MISS., Squadron:
A force of the enemy having been driven in from about 35 miles northeast from here. I sent out a force, about 12,000 strong, on the evening of the 26th. This force is commanded by Major-General Blair, and is instructed to clear out the enemy between the Black and Yazoo Rivers, and, if possible, destroy the Mississippi Central Railroad bridge over Black River.
There is great danger of the enemy crossing Black River in rear of this force, and cutting them off from their return to this place.
I have instructed General Blair in cases of this kind to strike for the Yazoo River, by which route a way back can be easily opened. If you can send one or two gunboats to navigate the Yazoo as high up as Yazoo City, I would think it highly advisable, at least until Blair is hear from.
U. S. GRANT
The Papers of Ulysses S Grant, Vol 8, p 286
O.R., I, xxiv, part 3, p 361