When Sherman started on his expedition down the river he had 20,000 men, taken from Memphis, and was reinforced by 12,000 more at Helena, Arkansas.  The troops on the west bank of the river had previously been assigned to my command.  McClernand having received the orders for his assignment reached the mouth of the Yazoo on the 2d of January, and immediately assumed command of all the troops with Sherman, being a part of his own corps, the 13th, and all of Sherman’s, the 15th.  Sherman, and Admiral Porter with the fleet, had withdrawn from the Yazoo.  After consultation they decided that neither the army nor navy could render service to the cause where they were, and learning that I had withdrawn from the interior of Mississippi, they determined to return to the Arkansas River and to attack Arkansas Post, about fifty miles up that stream and garrisoned by about five or six thousand men.  Sherman had learned of the existence of this force through a man who had been captured by the enemy with a steamer loaded with ammunition and other supplies intended for his command.  The man had made his escape.  McClernand approved this move reluctantly, as Sherman says.  No obstacle was encountered until the gunboats and transports were within range of the fort.  After three days’ bombardment by the navy an assault was made by the troops and marines, resulting in the capture of the place, and in taking 5,000 prisoners and 17 guns.  I was at first disposed to disapprove of this move as an unnecessary side movement having no especial bearing upon the work before us; but when the result was understood I regarded it as very important.  Five thousand Confederate troops left in the rear might have caused us much trouble and loss of property while navigating the Mississippi.

Immediately after the reduction of Arkansas Post and the capture of the garrison, McClernand returned with his entire force to Napoleon, at the mouth of the Arkansas River.  From here I received messages from both Sherman and Admiral Porter, urging me to come and take command in person, and expressing their distrust of McClernand’s ability and fitness for so important and intricate an expedition.

On the 17th I visited McClernand and his command at Napoleon.  It was here made evident to me that both the army and navy were so distrustful of McClernand’s fitness to command that, while they would do all they could to insure success, this distrust was an element of weakness.  It would have been criminal to send troops under these circumstances into such danger.  By this time I had received authority to relieve McClernand, or to assign any person else to the command of the river expedition, or to assume command in person.  I felt great embarrassment about McClernand.  He was the senior major-general after myself within the department.  It would not do, with his rank and ambition, to assign a junior over him.  Nothing was left, therefore, but to assume the command myself.  I would have been glad to put Sherman in command, to give him an opportunity to accomplish what he had failed in the December before; but there seemed no other way out of the difficulty, for he was junior to McClernand.  Sherman’s failure needs no apology.