Dr Nic Fields started his career as a biochemist before joining the Royal Marines. Having left the military, he went back to University and completed a BA and PhD in Ancient History at the University of Newcastle. He was Assistant Director at the British School at Athens, Greece, and then a lecturer in Ancient History at the University of Edinburgh. Nic is now a freelance author and researcher based in south-west France.

Gerry Embleton has been a leading illustrator and researcher of historical costume since the 1970s, and has illustrated and written Osprey titles on a wide range of subjects over more than 20 years. He is an internationally respected authority on 15th and 18th century costumes in particular. He lives in Switzerland, where since 1988 he has also become well known for designing and creating life-size historical figures for museums. His son Sam Embleton is also an illustrator, and this is their fourth joint project for Osprey.

By 390 BC, the Roman army was in need of change, as Greek-style tactics of fighting with a heavy infantry phalanx were proving increasingly outdated. A military revolution was born in the form of the legion, a tool of war better suited to aggressive action. Yet by the end of the 3rd century BC, Rome's prestige was shattered by the genius of Hannibal of Carthage, causing the Romans to revise their battle tactics once more, this time by inventing a whole new kind of soldier. This book reveals these two defining moments in Roman military history and the revolution in battle tactics that they caused, examining how the Roman army eventually became all-conquering and all-powerful.