A History of Warfare
Warfare from the Bronze Age to the nuclear era — not only battles and generals but culture, psychology, metallurgy, fortification, horses, weaponry, logistics, military organisation, ritual and the warrior ethos. Keegan's provocative claim is that war cannot always be understood as a rational continuation of policy: it predates the modern state and often expresses culture, identity, ritual, honour, religion and institutional momentum.
Read alongside Clausewitz. Keegan is deliberately attacking him, and Keegan's reading of Clausewitz has itself been contested. The value is in the confrontation: Clausewitz ties military action to political objectives; Keegan shows violence escaping rational control.