midnight
The most Rosecrans could do was to keep his cavalry in motion , reporting every movement the instant it was developed in front of the Army of the Cumberland . Bragg had concentrated his forces , and now he planned to strike one tremendous blow at a flank of the Union forces , and gain Rosecrans ' rear and his line of communication with his depot of supplies . For this purpose the Confederate leader divided his forces into two corps , one under Polk and the other under Longstreet , Hood commanding the latter temporarily . The troops advanced in the darkness , and by midnight held all the fords of the Chickamauga from Lee and Gordon 's Mill well toward Missionary Ridge . But meanwhile , the Army of the Cumberland was not idle . Crittenden was on the left , and Bragg was going to strike him . By a forced march along the Dry Valley road during the night , Thomas with his entire corps , and followed by a portion of McCook 's corps , reached a position facing the Reed and Alexandria bridges , now burned , -- thus making the left wing of our army virtually the right wing .