- Honorary Fellow, All Souls College (from 2014 to 2019)
- Honorary Fellow, Oriel College (from 1990 to 2019)
- Robert A. Lovett Professor of Military and Naval History, Yale University (from 1989 to 1993)
- Quondam Fellow, All Souls College (from 1980 to 2014)
- Regius Professor of Modern History and Fellow of Oriel College, Oxford (from 1980 to 1989)
- Chichele Professor of History of War (from 1977) and Fellow, All Souls College (from 1968 to 1980)
- Assistant Lecturer in History (1947), Lecturer (1950–3), Lecturer then Reader in War Studies (1953–63) and finally Professor of War Studies, King’s College London (from 1947 to 1963)
- Undergraduate, Christ Church, Oxford (from 1943 to 1946)
- History of war and international relations, primarily in the nineteenth and twentieth centuries
- Fellow of King's College London (FKC), President and co-Founder, International Institute for Strategic Studies
- Vice-President, Council on Christian Approaches to Defence and Disarmament
- President, Army Records Society Foreign Honorary Member, American Academy of Arts and Sciences
- NATO Atlantic Award (1989).
- Chesney Memorial Gold Medal, RUSI (1973).