Sir John Keegan (born 1934) is an English military historian specializing in 20th-century wars.
Keegan was born in Clapham, the son of Irish Catholics. He was educated at Wimbledon College for two years, then entered Balliol College, Oxford in 1953. He worked at the American Embassy in London for two years.
In 1960 he was appointed to a lectureship at Sandhurst, a post he held for 26 years. In 1986 he moved to the Daily Telegraph to take up the post of Defence Correspondent.
In 1998 he wrote and presented the BBC's Reith Lectures, entitled War and Our World.
He was knighted in 2000.
Frank C. Mahncke , a US defense analyst writing for the Naval War College, says of Keegan, "He is among the most prominent and widely read military historians of the late twentieth century" .
Keegan is admired for his ability to go beyond the traditional content of military history in search of a deeper understanding of war. His works treat the experience of the individual soldier, the historical causes of military events, the role of technological change in warfare, and the choices and dilemmas faced by military leaders. Recently he has received some criticism for his continued defence of David Irving, even after the exposure of Irving's fraudulent methods. In particular, his comments on Deborah Lipstadt, the Jewish historian who Irving sued, have been seen as unduly dismissive.
Despite being a military historian and lecturer, Keegan has never been in the military or in battle himself due to childhood illness, an irony he discusses in the introduction of a number of his works.