Heintges was born on 9 December 1912 in Koblenz, German Empire. His father was an officer in the Imperial German Army who was killed in action in the Battle of Tannenberg. In 1920 his family emigrated to the United States, sponsored by an uncle who was a major in the Army Medical Corps, and his mother remarried an infantry officer.[1]: 105–6
Following graduation from the United States Army War College, Heintges served in the Army Operations (G3) section. In 1954 he was posted to West Germany as Chief, Army Section, U.S. Military Assistance Group, Germany where he prepared and implemented the training plan for the West German Army.[3] From 1957 to 1958 he served as deputy commander of the Army Infantry Training Center at Fort Dix.[1]: 106
In 1958, Heintges was appointed as commander of Programs Evaluation Office (PEO) in Laos. In order to assume this new role he nominally resigned from the Army and served in Laos as a civilian.[1]: 106–7 During this time he developed the Heintges Plan to improve US assistance to the Royal Lao Army.[1]: 108–9
From 1961 to 1962, Heintges served as Director of Organization and Training, Office of the Deputy of Chief of Staff for Military Operations in Washington D.C. He served as commander of the 5th Infantry Division (Mechanized) in Fort Carson, Colorado from 29 January 1963 to 15 July 1964. He served as commander of Fort Benning from August 1964 to July 1965.
Heintges was promoted to Lieutenant General and was assigned as Commanding General, I Corps in South Korea from 1 August to 5 November 1965. In November 1965 he was appointed as Deputy Commander, Military Assistance Command, Vietnam (MACV).[4] In May 1967 he was succeeded in that role by General Creighton Abrams.[5]
Heintges then served as deputy commander, Seventh United States Army. He subsequently served as Deputy Commander in Chief United States Army Europe, in Heidelberg, West Germany, Deputy Commander of the Eighth Army in Korea, and U.S. Representative to the Central Treaty Organization in Ankara, Turkey. He retired from the Army in 1971.