The testudo formation in a Roman military reenactment. Soldiers used this shield wall to avoid a hail of arrows or other weapons. Photo by Neil Carey.
“Veni, vidi, vici.” I came, I saw, I conquered.
These words, reportedly spoken by Julius Caesar, exemplify Rome and its army.
At its height, Rome ruled most of the then-known world, stretching from Britain to Egypt and covering almost 2 million square miles. One of the main reasons the Empire became powerful enough to control such enormous swaths of land was its army.
Very advanced for its time, the Roman army boasted the best-trained soldiers, the best weapons, and the best armor. In the time of Augustus (27 BC to 14 AD), Rome fielded 28 legions for a total of 125,000 men. Each legio consisted of about 5,000 men. By 200 AD, there were 33 legions of about 5,500 men each.
During the Empire, the all-volunteer Roman army was made up exclusively of citizens. Most soldiers served the required 20-year term, though some served as many as 30 to 40 years. Legionaries were equipped with more expensive and protective armor than auxiliaries, were paid better, and served for shorter periods.
Centurions wore a transverse crest to be easily distinguished on the field. Legates and tribunes wore crests that ran from to back.
The legions were supplemented by smaller auxiliary forces—about 500 men to a unit. Auxiliaries were also mainly volunteers, non-citizens from allies and conquered territories, but for most of the 1st century AD they were also drafted. The auxilia contained heavy infantry, almost all the army’s cavalry (both armored and light), archers, and slingers. The men were rewarded with Roman citizenship after their term of service, and their children also became citizens and could join the Roman legions.
Legios were commanded by a legatus legionus. These generals were appointed by the emperor, chosen from the senatorial class. They received a large share of war booty, making the position well sought after. In a province with only one legion, the legatus also served as governor; in provinces with multiple legions, each legion had a legatus and the provincial governor commanded all of them.
The legate was assisted by 6 tribunes, approximately equivalent to a brigade commander. One, an inexperienced patrician son from the senatorial class, was designated deputy commander. This was his first job in the Empire, as it was just a stepping stone to political positions elsewhere. He was assisted by the praefectus castrorum or camp prefect, a veteran who had been promoted up through the centurionate.
The remaining five tribunes (from the equestrian class, just below the senators) served as the legate’s staff officers. Each commanded two cohorts of legionaries. These men had more experience than the senior tribune, having already served as independent commanders of an auxiliary cohort. After the tribuneship, an equestrian tribune could be promoted to command of a cavalry auxiliary.
Each legio had about 5,000 men, arranged in the following manner:
- 8 men made up 1 contubernium (mess unit/tentful), led by a file leader. These men shared a tent, a millstone, a mule and cooking pot.
- 10 contubernia formed 1 centuria (century). This was 80 men, but still called a century and commanded by a centurion (captain). Each century had its own standard.
- 6 centuriae made one cohors (cohort) of 480 men, commanded by its senior centurion.
- 10 cohortes constituted a legio (legion) of 4800 men, commanded by the legatus.
In the mid-first century AD, the first cohort was double-sized for a full legion strength of 5120. The primus pilus commanded this larger cohort.
Exhibit in the Cleveland Museum of Art, Cleveland, Ohio, USA. Photo by Daderot.
Each legion used an aquila (eagle) as its standard symbol carried by an officer known as aquilifer. This was an enormously prestigious position. The loss of a standard was considered to be total disgrace. Often it led to the disbanding of the legion itself.
Julius Caesar described an incident at the start of his invasion of Britain (55 BC) that showed how highly the standard was regarded. When his troops hesitated to leave their ships for fear of the Britons, the aquilifer of one of the legions jumped overboard carrying the eagle, advancing alone against the enemy. His comrades, fearing disgrace, ‘with one accord, leapt down from the ship’ and were followed by troops from the other ships. After a defeat in Germania, the Romans spent decades attempting to recover the lost standards of three legions.