From the Roman army's origins as war bands of farmer-warriors, mounting only brief, seasonal raids against their equally belligerent neighbours, the Romans developed a militia that adopted the weapons and tactics of the Greek phalanx. They then outstripped their rivals for power with the vital innovation of the 'manipular legion', a much more flexible and versatile battle formation. Fuelled by their willpower and resilience, the Romans' social and tactical organization enabled them to sweep away first the rival empire of Carthage and then the Hellenistic armies of the Greek world. Illustrated with battle plans and colour plates of formations and tactical scenarios, this book explains the development of the military machine that enabled Rome to dominate the whole Mediterranean.