Short answers, pulled from the story.
John Keegan was an English military historian, lecturer, author, and journalist born on the 15th of May 1934 in Clapham, London. He wrote extensively on the nature of combat from prehistory to the 21st century, covering land, air, maritime, and intelligence warfare as well as the psychology of battle. His books include The Face of Battle, A History of Warfare, The First World War, and The Second World War, among many others.
John Keegan contracted orthopaedic tuberculosis at age 13, which affected his gait and rendered him permanently unfit for military service. He was also too young to serve in the Second World War. He noted both facts in his own writing, describing them as an ironic observation on his career as a military historian.
John Keegan taught at the Royal Military Academy Sandhurst for 26 years, from 1960 until 1986. He began as a lecturer in military history and rose to senior lecturer during that tenure. He also held visiting positions at Princeton University and Vassar College during the same period.
In A History of Warfare, published in 1993, Keegan argued that war is inherently cultural rather than rational. He vigorously rejected the Clausewitzian idea that war is simply a continuation of interstate politics by other means. His treatment of Clausewitz was subsequently criticised as uninformed and inaccurate by scholars including Peter Paret, Christopher Bassford, and Richard M. Swain.
John Keegan was appointed Officer of the Order of the British Empire (OBE) on the 29th of June 1991 for service during the Gulf War, and was knighted in the 2000 New Year Honours for services to military history. He also won the Duff Cooper Prize in 1993, the Samuel Eliot Morison Prize for lifetime achievement in 1996, and received an Honorary Doctor of Letters from the University of Bath in 2002.
John Keegan died on the 2nd of August 2012 of natural causes at his home in Kilmington, Wiltshire. He was survived by his wife, two daughters, and two sons.