Walker resumed his brigadier general rank in the Confederate Army on February 9, 1863, and in May was assigned to brigade command to the Confederate Department of the West. On May 21 he was given divisional command in the same department, and he was promoted to major general on May 23. This promotion was strongly endorsed by the department's commander, Gen. Joseph E. Johnston, who considered Walker "the only officer in his command competent to lead a division." Walker then participated in the Vicksburg Campaign that summer in Johnston's command. Walker and his division were transferred to the Department of Mississippi &amp; Eastern Louisiana in July and served there until August 23, when his command was added to the Reserve Corps of the Army of Tennessee until November 4. During this time Walker fought in the Confederate victory at the Battle of Chickamauga in Georgia that September as commander of that corps.