Fuller transferred to the 11th Field Artillery in July 1917, and attended a course of instruction at Fort Sill. He was promoted to temporary Major on January 8, 1918. He sailed for France in October 1918 and joined the 108th Field Artillery at Véronnes. He participated in the Meuse-Argonne Offensive and commanded the 108th Field Artillery in the Battle of the Sambre, earning promotion to temporary Lieutenant Colonel on September 11, 1918. He commanded the 109th Field Artillery until March 1919 and then served with the Motor Transport Corps and Graves Registration Service.