Redesignation
In April 1864, the designation of the corps was changed to that of the XX Corps. Generals Williams and Geary still retained command of their divisions and the men still wore their XII Corps badge. This badge (a five-pointed star, or pentagram) was adopted by the reorganized corps. The new organization was formed by the consolidation of the XI and XII corps, to which was added some minor commands. This action of the War Department was based on the small sizes of the two corps: the XI had been extremely damaged at Gettysburg and the XII had always been the smallest in the army. Nonetheless, the soldiers of the XII Corps were very upset at the loss of their original corps identity.
Upon the discontinuance of the XII Corps, General Slocum was assigned to the command of the District of Vicksburg, but resumed the corps command—of the XX Corps—during the Atlanta Campaign, General Hooker having been relieved. Slocum afterwards commanded the Army of Georgia while on the March to the Sea and in the Carolinas Campaign.
Read more about this topic: XII Corps (Union Army)