HEADQUARTERS THIRTEENTH ARMY CORPS, near Port Gibson, May 3, 1863.

Major General U. S. GRANT, Comdg. Dept. of the Tennessee:

GENERAL: Your two dispatches are received. I have left one brigade of General Carr's DIVISION at Port Gibson, and ordered the SECOND brigade of DIVISION to halt at SECOND turn of the road to Willow Springs. The balance of my corps is on the way to Willow Springs, or to any point you may desire to have them halted. I have thrown two regiments out to the left, to feel for enemy on my left flank.

JOHN A. McClernand.

HEADQUARTERS THIRTEENTH ARMY CORPS, On the Road to Willow Springs, MISS., May 3, 1863.

Brigadier General E. A. CARR, Comdg. Fourteenth DIVISION:

GENERAL: General Grant informs me that he completed a bridge about 6 or 7 miles Port Gibson at sunrise, and that McPherson's column was encountered by the enemy. He also informs me that the enemy were re-enforced last night. Under these circumstances, he directs that a brigade be left at the crossing of the Bayou Pierre, on the direct road from Port Gibson to Grand Gulf-the same brigade I directed you to place to watch just before I left you. The same brigade will guard the new bridge we made over Bayou Pierre last evening, also our rear, by pickets to be posted along down Bayou Pierre as far as you well can.

The object, of course, is to watch the line of the Bayou Pierre. The remainder of your DIVISION you will post as favorably as possible at the forks of the road, where you turn directly to the left to reach the crossing of the south fork of Bayou Pierre, about 7 miles from Port Gibson. The forks referred to is the SECOND place where you take the left-hand road to reach the crossing at south fork of Bayou Pierre. McPherson moved on the same road from Port Gibson to the crossing referred to. It is desirable that you should keep up your communication between Port Gibson and the SECOND fort of the road referred to, by pickets, if possible. Report to me in advance often.

JOHN A. McClernand.

HEADQUARTERS THIRTEENTH ARMY CORPS, In the Field, Willow Springs, May 3, 1863.

Commanders of DIVISIONS will observe the following instruction until otherwise ordered:

The NINTH DIVISION, General Osterhaus, will advance to and hold the place where the Jackson road crosses the Willow Springs Branch or Ford, near Edin's farm.

The Twelfth DIVISION, General Hovey, will advance to and hold the place where the Vicksburg and Jackson roads fork.

The Tenth DIVISION, General [A. J.] Smith, will advance to and hold the place where the Vicksburg and Grand Gulf roads fork.

In bivouacking for the night, it is desirable that the different DIVISIONS should be so disposed as to enable them to be handled with facility and to support each other.

The artillery should be posted so as to enable it to command the surrounding [country].