Reimer's next duty was as assistant executive officer and aide to the Chief of Staff of the Army, General Creighton W. Abrams Jr., from 1972 to 1974. He served as executive officer and S–3 (Operations and Training), Division Artillery, 4th Infantry Division (Mechanized), Fort Carson, from 1975 to 1976. During this time he was promoted to temporary lieutenant colonel and permanent major in June 1975 and June 1976, respectively. He commanded the 1st Battalion, 27th Field Artillery Regiment, 4th Infantry Division (Mechanized) at Fort Carson, Colorado from 1976 to 1978, followed by assignment as commandant, Training Command, 4th Infantry Division (Mechanized).