The XVIII Corps was created on December 24, 1862. It was initially composed of five divisions stationed in North Carolina, making it one of the largest in the Union Army (though two were detached to join the X Corps in early 1863), and placed under the command of General John G. Foster. By August 1863, most of the corps' original units were either disbanded or transferred elsewhere, but Brig. Gen. George Getty's division (formerly of IX Corps) and the bulk of the recently discontinued VII Corps from Virginia were redesignated the XVIII Corps.