General Cushman earned a Masters degree in Civil Engineering at the Massachusetts Institute of Technology, then attended the U.S. Army Engineer School. In 1951 he transferred to the Infantry branch, attended the Infantry School, and joined the 22d Infantry Regiment, 4th Infantry Division, in Germany where from 1951-54 he was a battalion and regimental executive officer and battalion commander.
He was a student at the Army Command and General Staff College, then served three years on its faculty. In 1958-60 General Cushman was in the Office, Army Chief of Staff; in 1961-62 in the Office of the General Counsel of the Department of Defense; and in 1962-63, a military assistant to the Secretary of the Army.
In 1963 General Cushman became Senior Advisor to the 21st Division of the Vietnamese Army in the Vietnam Delta. In 1964-65 he attended the National War College, reporting thereafter to the 101st Airborne Division, Fort Campbell, Kentucky, where he was Director of Supply, Chief of Staff, and Commander 2d Brigade.
In December 1967, General Cushman led his brigade to Vietnam where it fought in the Tet 1968 battles around Hue. The 2d Brigade there earned the Vietnamese Cross of Gallantry with Palm. He then commanded Fort Devens, Massachusetts, returning to Vietnam’s Delta in 1970 for duty as Deputy Senior Advisor, then Senior Advisor, to the Commanding General, IV Corps and Military Region 4.
In 1972-73, General Cushman commanded the 101st Airborne Division, its colors just returned from Vietnam, at Fort Campbell, Kentucky. The draft having ended, he recruited the division under the Unit of Choice program and brought it to near full readiness. In 1973-76 he commanded the Army Combined Arms Center, Fort Leavenworth, Kansas, and was concurrently Commandant of the Army’s Command and General Staff College.
From 1976 to 1978, General Cushman commanded I Corps (ROK/US) Group, the 250,000-strong Korean-American field army formation defending the Western Sector of Korea’s DMZ and the ap-proaches to Seoul, He retired in 1978 and since then has been a writer and consultant. He is the author of many books and articles on strategy, multiservice and multinational operations, warfare simulation, and command and control of theater forces. In 1994 he was named “author of the year” for the U.S. Naval Institute Proceedings.