10 U.S.C. § 7063: Basic branches

(a) The Secretary of the Army may assign members of the Army to its basic branches. The basic branches are—(1) Infantry; (2) Armor; (3) Artillery; (4) Corps of Engineers; (5) Signal Corps; (6) Adjutant General’s Corps; (7) Quartermaster Corps; (8) Finance Corps; (9) Ordnance Corps; (10) Chemical Corps; (11) Transportation Corps; (12) Military Police Corps; and (13) such other basic branches as the Secretary considers necessary. (b) The Secretary may discontinue or consolidate basic branches of the Army for the duration of any war, or of any national emergency declared by Congress. (c) The Secretary may not assign to a basic branch any commissioned officer appointed in a special branch.