Welborn served in three other conflicts: the Philippine–American War, the Boxer Rebellion, and World War I, eventually rising to the rank of colonel. He served as a Tactical Officer at West Point, 1904–1906. After the tank was introduced to the battlefield in World War I, Welborn was detailed to be the first head of the fledgling United States Army Tank Service, for which he received the Distinguished Service Medal. He retired from service in 1932.