In the same way as the British Army is divided into divisions (usually 3 in an army), battalions (any number), companies (4 in a battalion) and platoons (4 in a company), each with a commander of certain rank (general, colonel, major and lieutenant respectively), the Roman Army was divided too. The most important section was the legion, which itself derived from the citizen militia staying in permanent preparation for war in defence of the state.
During the 2nd Punic War (q.v.) it was the strategist Scipio who was responsible for re-organising the battle array, thus improving the army’s tactics and strength.
Later, recruitment of ordinary young men without property of their own began, and in this way a fully professional force appeared, and new methods of training had to be introduced. Each cohort contained 600 men, and there were ten in a legion. Each legion had a name and a number with its own standard or flag, dominated by an eagle. Every century (100 men) was commanded by a centurion, so there were six centurions to each cohort. Are you still with me?
The cavalry and other fighting branches provided the support needed for each legion. It was Emperor Augustus Caesar (q.v.) who established a standing army to man the defences of the Empire’s frontiers. We are told by contemporaries that there were 28 legions, each, as we have pointed out, with its number and honorific title. Lucius Severus, Roman emperor (193 -211 AD) added three legions more. Emperor Constantine (the one who made Rome Christian) increased this number but reduced the legions to a thousand men each for two good reasons: to increase flexibility and (more importantly) reduce the possibility of mutiny. He also ordered the leaders to be mounted prefects, instead of the traditional senatorial legates, and put a Christian symbol (the Cross, a thousand years before the Crusades) on their standards.
When a legionaire retired (not many of them did or could) they earned a land grant called a ‘colony’ where they could continue the task of Romanizing and pacifying throughout the Empire. Here we see the origin of the word colony so important in the spreading (and understanding) of Empires fifteen hundred years later. It must be said that most legionaires preferred a straight gift of money upon retirement than a parcel of land. Nevertheless, many of these tough professional soldiers did settle in the area they found themselves in on retirement because of age or wounds, ending their days ‘colonizing’ it.