The army was formed on November 20, 1862, when General Braxton Bragg renamed the former Army of Mississippi and was divided into two corps commanded by Leonidas Polk and William J. Hardee. A third corps was formed from troops from the Department of East Tennessee and commanded by Edmund Kirby Smith; it was disbanded in early December after one of its two divisions was sent to Mississippi. The remaining division was assigned to Hardee's corps while Kirby Smith returned to East Tennessee. The army's cavalry was consolidated into a single command under Joseph Wheeler. The army's first major engagement under its new name took place against the Army of the Cumberland on December 31 along the Stones River. The attacks started at 6 a.m. against the Union right wing and forced the Union flank back towards the Union supply route to Nashville, but the Confederates were unable to capture the road. Bragg expected Union commander William S. Rosecrans to retreat during the night but Rosecrans decided to remain. No fighting took place on January 1; the next day Bragg assigned one division to seize a ridge on the east side of Stones River but the division's attack was repulsed by heavy artillery fire. Bragg retreated during the night and halted near the Duck River.