Has violence always been the final arbiter of human argument? Do other species conduct 'war' as opposed to the routine violence of the animal kingdom? When did ritualized, tribal conflict become 'organized' and hunting expeditions become armies? Doyne Dawson investigates the origins of human aggression, revealing the first weapons purpose-built to kill other humans. He shows how the earliest civilizations developed military institutions and dedicated war-making technologies from chariots to siege engines. His story concludes with the Assyrian Empire, a society organized for military conquest that had pioneered the use of terror - mass executions - as an instrument of state policy.