The First Oklahoma Infantry was mobilized for service in World War I on March 31, 1917. At Camp Bowie, Texas, the First Oklahoma combined with the Seventh Texas Infantry to form the 142d Regiment of the Thirty-sixth Infantry Division. The guardsmen arrived in France on July 31, 1918, and in October served around Blanc Mont Ridge and in the Ferme Forest. One of the machine gun companies was commanded by Captain Raymond S. McLain, who in World War II would attain the highest combat command position ever to be reached by a National Guardsman. This was as commanding general of the XIX U. S. Army Corps. The 142nd Regiment was part of the capture of St. Etienne on October 9, 1918. They were in reserve when the war ended on November 11, 1918. The troops were discharged in July 1919.