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,

LAKE'S LANDING, MISS., May 29, 1863.

Rear-Admiral DAVID D. PORTER, Comdg. MISS., Squadron:

Will you have the goodness to order the Marine Brigade to Haynes' Bluff, with directions to disembark and remain in occupation until I can relieve them by other troops? I have also to request that you put at the disposal of Major Lyford, chief of ordnance, two siege guns, ammunition, and implements complete, to be placed to the rear of Vicksburg. After they are in battery, and ready for use, I should be pleased to have them manned by crews from your fleet.

U. S. GRANT.

FLAG-SHIP BLACK HAWK, May 29, 1863.

General GRANT:

DEAR GENERAL: The brigade will leave for Haynes' Bluff early in the morning. I have not a 9-inch gun here-not anything larger than a 32-pounder (long range), excepting one 10-inch gun with shell. This would require too much work to mount it, on account of pivot-bolts, &c. I am fitting it on a mortar-boat, to throw shells into the pits in front of Sherman. I ordered two 9-inch guns sent to General McArthur at Warrenton. They are there now, on board the Tuscumbia, ready to be delivered. The difficulty will be in hauling them so far, though, perhaps, they may be in a better place for your purposes. I have six 8-inch guns on the Manitou, which vessel is now at Yazoo City. The moment she arrives, I will direct her commander to land the guns, and send to Cairo at once for more 9-inch guns.

Very respectfully,

DAVID D. PORTER.

NEAR Vicksburg, MISS., May 29, 1863.

Major General F. P. BLAIR, Jr.,

Commanding Advance Expedition:

Yours of the 28th, inclosing report of Colonel Johnson, is just received. It is so important that we should save all our troops to act together, that I would direct that you take no risks whatever, either of a defeat