 As a full colonel, he then activated the 345th Infantry Regiment at Fort Carson, part of the 87th Infantry Division.In August 1942, Collins was named as the assistant division commander of the 99th Infantry Division at Camp Van Dorn, Mississippi, and promoted to the one-star general officer rank of brigadier general.In April 1943, he assumed command of the 42nd Infantry Division (the famed Rainbow Division) at Camp Gruber, Oklahoma, and was promoted to the two-star rank of major general.