For over a thousand years the Roman army was continually at war and this continual state of aggression resulted in the Roman army becoming arguably the most efficient in the world.
In the second century BC the Roman Army consisted of four legions. Each legion comprising of about five thousand legionaries. The consul or preator in charge of the legion was helped by a legatus who was also a senator and by six young noblemen called military tribunes. The basic unit was made up of eighty men and was called a century they were led by a professional soldier called a centurion. Later each century was divided into contubernia - groups of eight men who shared a tent, a mule and a millstone.
At the beginning of each year the two consuls of Rome called all the land owning citizens aged between 17-46 to the Capitoline hill that overlooked Rome. Here the military tribunes chose the strongest men for the army. The men were not required to be soldiers full time though and were only required for specific conflicts.
The battles of the time tended to consist of two armies charging at each other and after the initial charge one side or other would turn and flee the battlefield. The Roman generals knew that if they were to be successful on the field of battle then they would need to train men who would be willing to stand and fight even when the odds were against them. The Roman army had to have discipline and any company that retreated was decimated (every tenth soldier was taken out and beaten to death with wooden clubs). Brave soldiers however were rewarded - a legionary who killed an enemy soldier was given a drinking bowl while the first man to scale the wall of a beseiged city would receive a gold crown. This determination coupled with the Roman tactics of warfare led the Greek writer Polybius to warn "it is inevitable that the outcome of every war the Romans fight is brilliantly successful."
The first Roman tactic was fairly staightforward and consisted in each soldier standing approximately four feet apart whereupon they would throw their pila (or javelins) at the enemy. Then they drew their swords and protected themselves with their shields - when men in the front rank fell another soldier would step into the gap.
The most famous of all the Roman tactics though was called the testula (or tortoise) and it consisted of the men forming a rectangle where the soldiers on the sides lapped their shields together and those on the inside held their shields above their heads to form a protective "shell" which protected them from missiles such as arrows and burning oil.
The Romans also used great war machines called balista which were giant catapults capable of launching huge boulders over an enemies defences. While covered seige towers and battering rams were used to protect the soldiers in the attack.
In 107 BC the consul Gaius Marius realised that Rome needed a permanent army if it was to enlarge its powerbase and he changed the rules regarding enlistment. He allowed men who did not own land to join the army as a career chpoice and after they had been in service for 16-20 years they would be given some money and a bit of land to farm. When not fighting or training the Roman army would be used to build roads, bridges and aqueducts.
By the first century AD the Romans had conquered most of the land that was to make up their empire and only a few more lands like Britain were added later on. The soldiers of the Roman army were used mainly to keep the empire safe from invasion and to quell uprisings from within the provinces. Although the Roman legions remained the backbone of the army, the auxiliary regiments (which included infantry and cavalry) became more and more important. It was their job for instance to patrol and guard the thousands of miles that made up the frontier of the Roman empire.
In peace or War the Roman army played an important role in society and many of the poorer people chose a career in the army because it gave them a good standard of living and the chance to learn a new trade such as building. Life in the army was tough and there were many things about the life that were not so appealling - they faced death in battle, they were not allowed wives but there were more benefits to the life that kept the ranks of the legions full. Most soldiers had unofficial wives and children and soldiers from the provinces were rewarded for their efforts in the army with citizenship of Rome.
Roman encampments and forts provided a ready market for the local traders and many of the settlements grew into cities such as Colchester in England. Intermarraige between soldiers and local women was not encouraged but it did have the benefit of welding the empire together.
The auxiliary cavalry were among the highest paid of all the Roman soldiers mainly because they had to pay for their horses needs out of their own pocket. The Italian Romans were not particularly good horsemen and so they raised mounted regiments where riding was commonplace such as Gaul, Holland and Bulgaria.
At the time of the invasion of Britain the Roman army was the most efficient and disciplined in the world. The legions that came over to Britain during the initial conquest were supported by auxiliary infantry and cavalry and although the auxiliaries were appreciated for their indiginous skills they were sent to the forefront of the battle as they were considered to be more expendable.
The centurions maintained a high level of discipline and continuous combat training. The initial training for a legionary lasted for four months and consisted of two sessions of weapon training a day with heavily weighted weapons to develop muscle. They also practised hand to hand combat with javelin and sword tips covered. Forced marches of 20-30 miles were common and building practice camps honed their skills in tree felling, timber cutting and making ditches and ramparts. Seige warfare was practised against abandoned hill forts. Every legionary also had to be able to swim and cook and have basic building and engineering skills.
A legionary on the march carried much more than his arms and armour. Each man carried a pack whcih held a tool kit and cokking utensils, this equipment would weigh over 90 lbs and was often carried up to 20 miles a day. Legionaries were called "Marius mules" after the emperor who started this practice.
There were many specialist craftsmen in a legion, such as the master builder, the surveyor, catapult maker, arrow maker and boat builder as well as regimental priests or soothsayers. They also had medical officers who were usually Greek and an injured Roman soldier could expect the some of best medical care in the world.
Wherever the army stopped for the night they always surrounded their camp with a ditch and earthworks topped by a palisade of pointed poles which the troops carried as part of their equipment. It took just a few hours for the legionaries to build enough ramparts and ditches to encompass 30 to 100 acres. A typical camp would cover approximately 50 acres and would have rounded corners (rather like a playing card). In the beginning they had earth ramparts and timber building but as time went on they were replaced by stone walls and buildings.
The headquarters building was always at the centre of the camp and would contain a hall large enough for the entire legion plus administrative offices, a strong room and a shrine to the emperor where the standards would be kept. The commanders house was next to the Headquarters and was built around a courtyard with its own bathhouse. The fort would also contain granaries, workshops and rows of barrack blocks all holding 80 men. The entire fort would be surrounded by a tall wall with a walkway for the sentries and turrets at regular intervals. The main bathhouse was considered a fire hazard and was built outside of the fort.
All of the Roman forts followed this pattern and smaller forts covering no more than 5 acres were found on Hadrians wall and provided bases for the auxiliary units and "fortlets" capable of holding 100 men were interspersed between the larger forts.