LEGIONS

The Legions were the backbone of the Roman military and it goes to show what a troublesome and unsettled frontier the North of Britain was that three Legions were left permanently based in this small country whereas somewhere the size of Spain warranted only one at the worst of times. At various times in the early Empire there were between 28 and 30 Legions around the world and each consisted of around 5,400 heavy infantry and cavalry. The Legions recruited only from Roman citizens who (although they became increasingly more common throughout the Imperial period) were a minority in places as far north as Britain.

Much of the Legion's manpower was not just a standard frontline combatant, but were also scribes, engineers, architects, blacksmiths, carpenters, medics and other specialised careers. This enabled the Legion to take care of itself under almost any situation and is the reason that not only were all the military installations in Britain built by the Legions, so were many of the civil edifices. These men were the 'immunes' (men who were excused from standard duties).

Each Legion was split into 10 Cohorts and Cohorts 2-10 of each Legion would consist of 480 men split into 6 Centuries of 80 and each led by a Centurion. The 1st Cohort of each Legion contained the highest ranking and most experienced officers and the best veteran troops. This cohort would number 960 men split again into 6 Centuries of 160. The lowest unit of men was the 'contuberium' of 8 men. These men would share certain communal items and would share a tent, which they would carry in pieces between them. The Legion also had a detachment of 120 light cavalry that served not as fighting men, but as scouts and messengers.

In command of a Legion was a Legatus (Legate) that was an Imperial appointment for the highest ranking Patrician classes. Some such officers became great and famous military men (such as Vespasian who led the 2nd Augusta in Britain), while others were politicians with little military experience. As an aid to the Legate, 6 Tribunes were assigned from the higher classes of Citizen and these could often be men of good military experience. The true military knowledge and experience of the Legions, however, lay with the Centurions, 60 in number and of varying rank.

Often situations called for experienced Legionary troops, but in much smaller numbers than the entire force, and detachments (or 'Vexillations') of varying size would be sent to fulfil a task, leaving the rest fo the Legion at their home fortress. In addition to the three Legions permanently stationed in Britain, there is often evidence of 'vexillations' from Legions based on the continent being sent to Britain to help with insurrections or even with building projects.

Legions were each given a number, though numerals were reused, leading to two 2nd Legions. Thus Legions took names for themselves. The 2nd Legion Augusta were the 'August' Legion, while the 2nd Legion Adiutrix were the 'Helper' Legion. Other names were taken on in pride or recognition, including epithets of Emperors' names or such words as 'faithful' or 'predatory'.

AUXILIARY COHORTS

The auxilia actually formed the large part of the Roman military. Of varied skills and purposes, they were smaller units of less well-trained and well-equipped troops. They formed Cohorts that generally numbered 500 (quingenary) or 1000 (milliary) and were either infantry, cavalry or 'equitata' (part infantry, part cavalry.) The cavalry units are known as ala (pl. alae) which roughly translates to a 'wing' of cavalry. Cavalry units almost always numbered 500, the only exception in Britain being the Ala Petriana, based at Stanwix on the wall.

The auxiliary cohorts were drawn from the non-Citizen class and one of the major incentives for recruiment was that after a full term of service the soldier received citizenship.

The cavalry Alae were split into 16 'turmae', each consisting of 32 troopers. Infantry cohorts were split into either 6 or 10 Centuries of 80 men depending on the size of the cohort. Equitata Cohort organisation is not known for sure.

In command of an auxiliary unit was a Tribune, similar in status to the 6 tribunes attached to a Legion and of similar background. Below these there were the various Centurions of infantry units and their cavalry equivalents, Decurions, commanding a Turma. As the forts visible in Britain are auxiliary forts (with exceptions like York, Chester and Caerleon), their layout reflects the organisation of the unit and since their is only one senior officer in an ala or cohort, there is a commanding officer's house in each fort. This is more complex in Legionary fortresses where there are 7 senior officers.

Much like the Legions, Auxiliary units were given a numeral that was often reproduced, and were further identified by additional names. In the case of auxiliary units, however, this was usually the Province where the unit was founded or the tribe from which is was drawn. Thus in Britain we see the 1st Cohort of Gauls and the 5th Cohort of Gauls, along with the 1st Cohort of Thracians and the 5th Cohort of Raetians. Like the Legions, they sometimes took other names in recognition, such as Emperor's names (units with the epithet 'Gordiana' for example), names of previous commanders or even the epithet 'Citizens of Rome' in some cases (which must have been granted en-masse to the unit for some great deed.)

Auxiliary units may have had nominal strengths of 500 or 1000, but as one of the tablets found at Vindolanda (mid 2nd century) shows, this was not always the case. The 1st cohort of Tungrians at Vindolanda had a strength on paper of 752. In actual fact the number of fit and active men in the fort numbered 256.

PRAETORIAN GUARD

The Praetorian Guard were never stationed in the Provinces, as they were based in Rome itself. However, during those times when Emperors visited Britain, detachments of the Guard will have accompanied him, fighting at times (for instance during campaigns under the command of Claudius or Septimius Severus.)

The Praetorian guard were the prestigious elite of the Roman military, numbering less than a Legion in total, with 9 Praetorian Cohorts numbering 500 men each.

THE LATE EMPIRE

The army of the late Empire is signifantly different, although the changes were probably gradual rather than a wholsale reorganisation. Legions still existed at the end of the period, but were now much smaller and devoted to the protection of the borders along with the auxiliary units, though the gap in training and equipment between the two types of unit closed by a long way. These two trypes of unit formed the limitanei (the troops who defended the borders.)

Less stress was paid to these, however, than to the new mobile field armies that begin to appear from the late third century. These are larger forces consisting greatly of cavalry, that are based in central areas in order to react fast to threats. These armies were initially under the command of the Emperors, but later were found in the provinces with the British Field Army being under the command of the Comes Britanniarum.

In addition to these, there were a large number of Numerus and Cunea (smaller units numbering maybe a couple of hundred men) who become named after the fort at which they are based and have specific skills or duties. Scouts are noted at places like High Rochester, while South Shields in the late empire is home to a 'Numerus' of Boatmen from modern Iraq or Turkey.