The 129th Infantry Regiment is a United States military unit of the Illinois National Guard. The 129th served in World War I and World War II. Initially part of the 33rd Infantry Division during World War I, the 129th Infantry Regiment was detached on 31 July 1943, sent as the Espiritu Santo garrison force and later attached to the 37th Infantry Division on Bougainville during the Bougainville campaign on 13 November. The regiment is now known as the 129th Regiment (Regional Training Institute), providing training. 129th Infantry Drive in Joliet, Illinois is named in honor of the regiment.