The Army of the Ohio was at the time marching toward Chattanooga, and was strung from Eastport by Huntsville to Bridgeport, under the command of General Buell.

In like manner, the Army of the Tennessee was strung along the same general line, from Memphis to Tuscumbia, and was commanded by General Grant, with no common commander for both these forces: so that the great army which General Halleck had so well assembled at Corinth, was put on the defensive, with a frontage of three hundred miles.

Soon thereafter the rebels displayed peculiar energy and military skill.

General Bragg had reorganized the army of Beauregard at Tupelo, carried it rapidly and skillfully toward Chattanooga, whence he boldly assumed the offensive, moving straight for Nashville and Louisville, and compelling General Buell to fall back to the Ohio River at Louisville.
The army of Van Dorn and Price had been brought from the trans-Mississippi Department to the east of the river, and was collected at and about Holly Springs, where, reenforced by Armstrong's and Forrests cavalry, it amounted to about forty thousand brave and hardy soldiers.

These were General Grant's immediate antagonists, and so many and large detachments had been drawn from him, that for a time he was put on the defensive.