Commanding Thirteenth Army Corps:
A portion of the Ninth Army Corps, about 8,000 strong, have now arrived, and will take position on the south side of the city, thus making the investment complete. This will release General Herron, who is instructed to move to General Hovey's place, thus contracting your front to the ground occupied by Smith and Carr.
Should the enemy attack Haynes' Bluff in such force as to make it necessary to detach a greater force than has already been designated, i.e., the six reserve brigades of McPherson's and Sherman's corps, I will have to entirely uncover on the south side of the city. This will necessarily involve an exposure of our left flank from the garrison of Vicksburg. We should hold and fight the enemy wherever he presents himself, from the extreme right to your extreme left—that is, all the ground taken by the three army corps on first investing the city should be held.
Your left division is, or will be, replaced by one numerically stronger. By replacing it thus it gives you a reserve of three brigades. Lauman's, with nearly 6,000 men, will also be there to strengthen you still further in this emergency.
I do not want to give up the front occupied by Lauman unless it should become absolutely necessary to do so, but give this as a plan to be adopted in case of the greatest pressure on the left. The idea, then, is, that two lines should now be selected running perpendicular to our present line, one from Lauman's left, along Hall's Ferry road, and one from Hovey's present left. Should Parke's command, the Ninth Corps, be removed, your reserve should at once be thrown on to the first line chosen on the Hall's Ferry road. Should they be so hotly pressed as to make it necessary for them to fall back into the second line, then Lauman's division should be brought into it also. The very moment an order goes for the removal of the Ninth Corps you will be notified. You will then assume command of all the forces to the left of you in addition to your own corps.
Everything in the shape of ammunition, commissary stores, and other public property not required, should be got back to within what may possibly become our most contracted line.
Should the enemy attempt to get past your left, with the view of forming a junction with Johnston's forces, he must be defeated. An attempt to leave his lines, however, I do not look upon as probable. This would give us the city, and leave my whole force to act directly against the enemy, and as a last resort fall into his lines, and act on the defensive, behind works of his own building. This is given only as a general plan, to be adopted under certain circumstances. The movements of an enemy necessarily determine counter-movements.
After writing the foregoing, and after General Parke had moved one division of his command to opposite Warrenton, I had to change my plan and send him to Haynes' Bluff. From information received, the enemy have 12,000 infantry and artillery at Yazoo, with orders to move south; four thousand cavalry already between the Yazoo and Big Black River, and Loring ordered to cross. This made it necessary to send the extra force up the Yazoo River.
You will assume command of Lauman's division at once, Herron taking up part of the ground occupied by Lauman. The latter can better spare a garrison regiment to garrison Warrenton than any one else. I would not take a regiment from you for a garrison of Warrenton, but Herron has a long line to hold, and but eight regiments to do it with.
Lauman will be directed to report to and receive orders from you.
U.S. GRANT.
