Military History

Roman Military History


Roman military organization was...rather undeserving of the word ‘organization'. Bear that in mind. Most people will probably find the exact details a little boring, but I've included them anyway. Also - there's a lot of contradictory information out there on the structure of the Roman army, and a few things that nobody's really sure of, so it's entirely possible that I could be misinformed on some of the details. I apologize for any mistakes I might make.

In the Republican Legion, which is what the legion up to Marius is referred to as, legionnaires were divided into three categories according to age/experience: the hastati, principes, and triarii (triarii being the most experienced, and equipped with a melee spear rather than throwing javelins – in addition to the swords they all carried).

There were 20 centuries of each of these types of infantry. The centuries of hastati and principes consisted of 60 men each, and those of triarii had 30 men each. Centuries were organized in groups of two, known as maniples. Thus there were 10 maniples of hastati and principes (10 maniples x 2 centuries per maniple x 60 men per century = 1200 men each), and 10 of triarii (10 x 2 x 30 men per century = 600). This works out to 1200 + 1200 + 600 = 3000 legionnaires, who along with the 1200 velites (lightly armed skirmishers, who were used as a vanguard ahead of the main infantry formation) came to 4200 men. The infantry maniples were normally organized in a checkerboard pattern on the battlefield. The Republican legion also had roughly 300 cavalry.

Marius removed the existing land requirement for enlisting in the military, thereby opening the service up to a far larger group of Romans. However, since they did not own land, many of them were also more dependent on their salaries, and therefore more likely to be loyal to their commander over the Republic...as proved to be the case more than once. After the Marian reforms, the legion looked very different. Its basic unit of organization was now the contubernium, which consisted of 10 men – the three types of infantry had been abolished. 8 contubernia made a century (80 men); 2 centuries were still a maniple (160), 3 maniples were a cohort (480), and 10 cohorts made up the Marian legion (4800 legionnaires). The ala, or cavalry wing, remained at 300 horses, although this may have been increased later.

The Roman army always fought with auxiliary troops at its side. Auxiliaries were provided by allies or subject people, and were normally roughly equal in size to the number of Roman troops they were supporting. Cavalry was an exception; since the Romans had almost no cavalry to speak of themselves, allies were often relied on to provide this crucial part of the army. Although auxiliaries were originally allowed to organize themselves in any manner (which makes sense, since they were sometimes commanded by their tribal chieftains, for example), they later were placed into more structured units of five hundred or a thousand men.

Officers – any Roman army was commanded by an appointee of the Senate, known as the Legate. Under him were six military tribunes (not the same as the tribunes of the people in the Roman government), who were normally younger men from aristocratic families carrying out their military service, either because they wanted a military career or because it helped when running for office. There was a senior professional officer known as a prefect to help the legate (who, being a political appointee, might know nothing about military affairs), and then a complex system of six kinds of centurions, the Roman equivalent of our sergeants – the backbone of the army, really. Each century was commanded by a centurion, with an assistant known as an optio. There were also officers who were in charge of sentries (tesserarius) and the legion's standards (aquilifier).