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Sherman, and Admiral Porter with the fleet, had withdrawn from the Yazoo.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they decided that neither the army nor navy could render service to the cause where they were, and learning that I had withdrawn from the interior of Mississippi, they determined to return to the Arkansas River and to attack Arkansas Post, about fifty miles up that stream and garrisoned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.