Gaius Julius Caesar remains the most famous Roman general of all time. Although he never bore the title, historians since Suetonius have judged him to be, in practice, the very first 'emperor' – after all, no other name in history has been synonymous with a title of imperial rule. Caesar was a towering personality who, for better or worse, changed the history of Rome forever. His unscrupulous ambition was matched only by his genius as a commander and his conquest of Gaul brought Rome its first great territorial expansion outside the Mediterranean world. His charismatic leadership bounded his soldiers to him not only for expeditions 'beyond the edge of the world' – to Britain – but in the subsequent civil war that raised him to ultimate power. What is seldom appreciated, however is that the army he led was as varied and cosmopolitan as those of later centuries, and it is only recently that a wider study of a whole range of evidence has allowed a more precise picture of it to emerge. Drawing on a wide range of new research, the authors examine the armies of Julius Caesar in detail, creating a detailed picture of how they lived and fought.