He worked as the private secretary of William Cary Renfrow when he was the governor of Oklahoma Territory.

"[2] Hoffman was involved in the American Legion, serving as a charter member, organizer, three-term national executive committee member, and as the national vice president of the American Legion Founders.

Hoffman was promoted to the rank of brigadier general on August 5, 1917, and he assumed command of Fort Sill.

Hoffman then assumed command over the 61st Depot Brigade at Camp Bowie, and he helped organize the 36th Infantry Division.

[1][3][4] After he returned to the U.S., Hoffman commanded Camp Shelby and the 101st Division before being honorably discharged from the National Army in March 1919.

He retired as a major general of the Oklahoma Army National Guard in 1933, commanding the 45th Infantry Division.