The Imperial Roman Army

This is my topic on the Imperial Roman Army. In this topic I will be talking about the Legions, the organisation of the legions, the weaponry, the Officers, the Non Commissioned Officers (NCOs), and other special units such as the auxiliary troops, The Praetorian Guard, The Imperial Guard, and the Imperial horse guard. Please note that all of the given information is based on the information of the Imperial legions, which date from the first few centuries AD, not the Republic Army, which was quite different.

The Legions
The Legions were the backbone of the Roman Army, and in their time the best troops in the whole of the known world.
The troops in the legions were typically Roman citizens, but this does not mean that they came from Rome, or even Italy, the Roman Empire spread from the deserts of Africa to the boarders of Scotland, at that time the about three quarters of the known world, and most people in it became Roman citizens if they wished. The legion or legio in itself was a miniature army. In the ranks most would serve as heavy infantry, though there were some who fought as cavalry, archers, or light infantry. There were also many men who had special skills, such as blacksmithing, engineering, so in many ways the legion was self-supporting.
Each legion would carry it’s own number and name, e.g. legio X Gemina (the tenth twin legion) to which honorary titles such as pia fidelis (dutiful and loyal) could be added for feats of bravery or for winning battles. In many ways this happens today, a Squadron or a regiment is given a number and a motto, e.g. 51 Squadron celeriter defendere, so in lots of ways the modern army is a bit like the Roman army.

Organisation of the legions
There was probably no standardised organisation throughout the Roman rule, but usually the legion was made up of ten cohorts, these cohorts were then divided in to centuries, although the name century would suggest 100 men, it was in-fact around 80, as the system had change since the republic. In turn the centuries were divided into tent parties of eight men. The commander of each century was called a centurion, there were also the optio, these served as the sergeant and corporal, there was also the signifer who was the standard-bearer. The first cohort of the legion was made up to double strength centuries.
Each legion also contained a body of 120 horsemen who acted as scouts and dispatch riders; they were not organized as a formal unit but were allocated throughout the legion. Each cohort had one ballista (stone-thrower) and each century one scorpio (bolt-shooter). Although in practice each legion used only 50 or so such weapons. The scorpio and ballista were used mainly for sieges, though sometimes the bolts and stones were set alight for use against tightly packed infantry.

Weaponry and Equipment
The legionary carried two main kinds of offensive weapons, which were the gladius (sword) and pilum (javelin).
The gladius was a double bladed weapon some 60cms long and 5cm wide. It often had a bone grip, which was corrugated. It was carried high on the right-hand side in its scabbard, to be clear of the legs and the shield arm. It was used for thrusting rather than swinging, as here would be no room to swing it in the closely packed ranks.
The pilum (spear), of which each legionary carried two, was 2.1 metres long including its iron head. It had an effective killing range of just over 27 metres. The head was devised so that when it pierced the shields of the enemy, the iron head would bend making it impossible to pull out, it would then become very cumbersome to the holder of the shield. In most cases the shield would be thrown away.
Each legionary also carried a pugio (dagger) this was attached to the left-hand side of the belt. The pugio was between 22.5cm and 25 cm in length.
Each legionary carried a rectangular shield (Scutum), which was curved to fit the body. It was made of plywood bound at the edges with metal strips of wrought iron or bronze. The centre was hollowed out on the inside for the handgrip and protected by the metal boss; this would be used to hit the enemy in the face with. Two leather straps were fitted to the inside of the shield, one for the forearm and the second to enable it to be slung from the left shoulder when on the march. The outside surface was covered in leather and decorated.
Body armour varied from time to time, under Caesar, and in the early first century the legionary wore mail. By the time of Claudius a complex suit of six or seven metal horizontal strips attached on the inside by leather strips to allow movement. The shoulders were covered with sets of curved strips and there were also paired front and back plates. The armour could be put on as one piece and laced up. This type of armour looked like fish scales, the different plates over lapping each other, this would deflect most blows.
The helmet had been carefully designed - it was made of bronze with an inner iron skull-plate. At the back a projecting piece shielded the neck. A small ridge fastened at the front gave protection to the face. At the sides were large cheek-pieces hinged at the top. As with body armour, helmets varied from time to time. It is possible that all helmets had plume-holders. Plumes were only worn on parade and had the appearance of small upright feathers fixed on top of the helmet. It is probable that for special occasions other plumes would be used.

Officers and NCOs
The legionary commander was the legatus legionis, formally a senator, and appointed to command a legion by the Emperor. In some provinces he would have to combine the roles of legion commander and that of provincial governor. His previous military experience would have been as a tribune.
For the day to day running of the legion, the commander would depend heavily on two of his officers, the primus pilus and the praefectus castorum. The praefectus castorum was the camp prefect. He was the equivalent of a modern day quartermaster and was responsible for engineering and building works, and transport of and for the legion. In the legions hierarchy he ranked third, behind the commander and the tribunus laticlavius.
Below the commander there were a group of semi-professional officers - the tribunes, of which there were six. The most senior among them was the tribunus laticlavius.
The five other tribunes known as angusticlavii, would have had previous military experience, having served in an infantry auxiliary unit.
Below the tribunes came the centurions. These were the only officers who permanently commanded legioinaries, most of whom had risen from the ranks. They were the only lifetime officers in the legion and many of them had served over their obligatory 25 years, and were seen by as the backbone of the army. Others from outside the legion could apply for a commission as a centurion, for example anyone who had completed their 16 years of service in the Praetorian Guard.
In each legion there were 59 centurions.
The first cohort was divided into five double centuries and commanded by the most senior centurions who were known as primi ordines.
The most senior of them being the primus pilus, followed by the princeps, then the hastatus, then the princeps posterior and finally the hastatus posterior.
Although centurions had at least 25 years service, it was more than likely to have been spent with several legions. Transfers between legions were commonplace. Usually because many Vexillations were absorbed into legions to make up for the heavy losses they may have suffered during a campaign.
Vexillations were detachments of troops from a legion in a peaceful area of the Empire who were sent on campaign.
Under the command of the centurion was the optio who was his second in command and would take over from the centurion if he was killed or injured.
Each century also had a signifer or standard bearer who acted as treasurer for the soldiers burial club. A further junior officer was the tesserarius, who was responsible for and commanded small pickets and fatigue parties.
Each century also had a librarius who was a clerk and a cerarius - which means, a writer on wax tablets. The senior officer below the rank of centurion was the aquilifer, the standard bearer who carried the legions silver eagle - which was the most sacred symbol of the legion. It was the worst disgrace possible to loose the legions eagle, any legion that did so would be disbanded. Below him was another standard-bearer called the imaginifer who carried the image of the Emperor.

An Imperial Legion On The March
The Jewish historian Josephus left an account of the Roman army on the march during the Jewish revolt in 66 AD. It was written some 200 years after the Roman historian Josephus, a Jew and Polybius, a Roman left us accounts about the Roman army on the march, Josephus wrote it at the time of the Jewish revolt in 66 AD, two hundred years after Polybius wrote his account, what is so remarkable about the two works, is the fact that they are almost identical. Yet Josephus did not copy from the earlier work.
Cavalry and auxiliary infantry would scout ahead as a precaution against ambushes.
The vanguard would consist of a legion and a force of cavalry; each day the legions would draw lots to decide which would form the vanguard.
Following the vanguard would come the camp surveyors who would mark out the camp for that night; the pioneer troops would follow them. It was the task of the pioneer troops to clear any obstacles in the way of the column. If a river had to be bridged then they would build it.
Next came the Generals personal baggage and its mounted escort, followed by the General himself and his bodyguard.
The legionary cavalry, (combined from all the legions) was next with the dismantled siege engines - towers, rams, catapults carried by mules behind them.
The senior officers, who were the legates, tribunes and auxiliary prefects, came next with their escort.
The legions followed each other headed by their own aquilifer and other standard bearers of the legion. Its own baggage train controlled by the legions servants followed each legion.
The auxiliary cohorts each led by their own standard bearers would follow the legions.
At the end of the column was the rearguard; this would consist of light and heavy infantry as well as a considerable number of cavalry.
The camp followers would be found close to the rearguard for protection. These would include merchants of all kinds, common-law wives, prostitutes and slave dealers ready to buy up the prisoners of war.

The Imperial Guard
The Roman Emperor had several units at his disposal. The most important of these being the cohortes Praetoriae or Praetorian Guard. Also during the reign of the Julio-Claudio dynasty the Germani custodes corporis or German bodyguard were also installed for additional security. The equites singulares Augusti recruited among the Auxiliary cavalry formed the Emperor’s horse guard. Most of these men served as guards, and would not look over the person of the Emperor directly. These forces formed the Elite of the army in a field army assembled for Imperial military expeditions. Small numbers of soldiers were selected among these guard units for personal protection duties.

The Praetorian Guard
Under the republic the generals had formed a unit know as cohors praetoriaI, after the praetorium, or the HQ. However, under the Empire such units became reserved as the Emperors body guard who he would command when he was on campaign. One Praetorian unit consisted of about 50 infantrymen, who were organised into manipuli and centuriae and under the overall command of a tribunus. This strength doubled in the first century AD. The majority of Praetorians fought as heavy infantry with smaller numbers acting as light infantry lancerii and archers, each cohort would also contain a small detachment of cavalry.
There were other troopers known as equites Praetoriani, who served as bodyguards to the Emperor. The Praetorian cohort that guarded the Emperor in the city of Rome was known as the cohors togata.
Life was much better in the Praetorian Guard than the ordinary legions, the pay was substantially higher, and promotion opportunities were also excellent, as Praetorian Guardsmen usually took up empty centurion posts. The Praetorian Guard originally served as the backbone of field armies when the Emperor, one of his relations or a praefectus praetorio.

The Imperial Horse Guard
Members of the Imperial horse guard were usually recruited form the alae or cohortes equitatae, though sometimes men were directly recruited. The cavalry training officers, or centuriones exercitatores were not drawn from the auxilia, but from the legionary cavalry. The strength of the Horse Guard was around a thousand troopers strong, a number eventually doubled by Septimius Severus. The organisation of the horse guard resembled that of the auxiliary cavalry. An equestrian tribunus functioned as overall commander of the Horse Guards.

The Auxilia
The Imperial Roman army carried on with the Republican tradition of supplementing the citizen legions recruited from, what was know as peregrini, which were non Roman citizens from conquered or allied countries. The Imperial auxilia units were composed of a variety of units. The infantry were organised in cohorts, which in the case of the cohortes equitatae could include a small amount of cavalry. Cavalry was formed in to units called alae, which means wings. Both cohortes and alae could compromise either quingenaria units of about 500 men, or milliaria, which were formations of 800-1000 troops. Auxiliary formations were usually commanded by a praefectus cohortis or praefectus alae. The command of cavalry units was given to men who had formally served as praefectus cohortis or legionary tribunus.
Cavalry turmae were placed under a decurio instead of a centurion. Legionaries would often transfer to become officers and NCOs in the units of the auxilia. Like to legions, the auxilia units would carry a name, number and a title. Units of archers formed a large proportion of the available auxiliary forces. The alae were mainly made up of medium cavalry, which were suited for both skirmishing and shock tactics. Formations of mounted archers would also be employed.

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