The Roman Army in England
INTRODUCTION
The army that invaded Britain in 43 AD at the command of the Emperor Claudius differed in structure from the one that gradually slipped under local control as the province became independent in the fifth century. This change is reflected in the types of sites the army used and the structures it built. Timber and earth forts some intended for one winter’s or summer’s use during the first century became more permanent structures built or rebuilt in stone. During the second and third centuries they were given towers to provide flanking fire along the walls as the army began to contemplate its bases coming under siege. And by the fourth century the classic playing card ground plan of forts was becoming replaced by irregular shapes that took advantage of defensive locations and begin to suggest medieval castle plans.
The auxilia provided the army’s cavalry and light infantry. Their units were 500 – 1,000 strong and normally recruited from non-citizens. Auxiliary soldiers received citizenship when they retired. Auxiliary regiments were grouped into army groups based on a legion and under the command of the legion’s commanding officer. Normally there were the same number of auxiliaries as legionaries in these army groups.
HOUSEHOLD TROOPS
In the early empire the Emperor had under his direct command the Praetorian Guard and his cavalry body guard – the Singulares both based in Rome.
Singulares was the name given to the body guard of the Emperor, governors or generals. The British singulares would have been based in the Cripplegate fort in London and have been made up of men seconded from the rest of the British garrison.
Legions consisted of ten cohorts, with six centuries of 80 men in each cohort, apart from the first cohort which from around 70 AD was double strength, ie six centuries of 160 men. There were also 120 mounted troops to act as messengers and scouts. The legion’s commanding officer was the legate; appointed from the senatorial class by the Emperor. The other senior officers were six tribunes and 60 centurions.
Detachments from legions or occasionally from auxiliary regiments operating on their own or with other detachments were known as vexillations (from the flag that identified them that was known as a vexillatio) and until the creation of field armies in the late Empire were the way of providing temporary reinforcements to provincial armies for major campaigns. It is presumed that this practice of creating vexillations for the field armies gave rise to the increase in the number of legions in the late Empire and their reduction in size to units of around 1,000 strong.
- II Augusta (reformed from an earlier legion by Augustus), in Britain for the whole time that Britain was in the Empire and last recorded at Richborough in the Notitia Dignitatum (late 4th early 5th century)
- II Adiutrix pia fidelis (raised from sailors at Ravenna, supported Vespasian’s bid for the throne, the title means supportive, pia fidelis given by Vespasian to mark its faithfulness to his cause), in Britain from circa 70 AD until the late 80s AD
- VI Victrix pia fidelis (raised by Augustus, victrix may refer to a victory in Spain, pia fidelis awarded by Domitian), it arrived in 122 AD and was still present at the end of the fourth century?
- VIIII Hispana (gained its title from Spanish campaigns in the first century BC), was part of the invasion army, left the province around 110 AD
- XIV Gemina Martia Victrix (Gemina implies either one legion made from two or two legions made from one original, martia victrix from its role in defeating Boudica), part of the invasion army, left in 66 AD and temporarily returned around 70 AD before leaving permanently soon after
- XX Valeria Victrix (valeria victrix from its role in suppressing the Boudican revolt? or from Agricola’s campaign in Scotland?), part of the invasion army, last recorded in Britain at the end of the third century.
Other legions are recorded as serving in Britain. These are evidence either of vexillations to reinforce the garison or the ‘home unit’ of officers commanding auxiliary regiments. A vexillation of 1,000 men each from the VII Gemina, VIII Augusta and XXII Primigenia for example is recorded on the tombstone of the commnading officer.
Infantry
Infantry units known as cohors peditata had six centuries with 80 soldiers to each; milliaria cohorts had ten centuries (like a legion’s first cohort).
Auxiliary units were commanded by tribunes drawn from the equestrian class, second to senators in status, with centurions leading centuries and decurions turmae.
Legions and auxiliary units would rarely be at full strength. Sickness and the provision of men to assist the civil administration could reduce units to around half their theoretical strength. Full complements might have been only achieved at the beginning of campaigns. Writing tablets excavated at Chesterholm and listing unit rosters show that units could often be considerably under strength and that regiments might also be divided between several forts, sometimes mixed with troops from other units. Despite their unit titles regiments recruited locally. Ala Gallorum although initially raised in Gaul, would have started to recruit locally once in Britain and would have been made up of Britons by the time it moved to Germany in the 120s AD.
Fleets (classis) provided the Empire with both sea power and logistical support. In Britain until the late third century the Classis Britannica appears to have operated almost entirely in the logistics role: transporting the invasion army; provisioning the units in northern Britain; and managing the iron industry in the Weald of what is now Kent and Sussex.
The army’s role remained much the same in both periods: policing frontier tribes; preventing cattle rustling and tax evasion; and showing the flag to allied tribes in the border region. However the increasing sophistication of the tribes outside the Empire, caused in some ways by the presence and success of the Empire itself, meant that wars in the later Empire, when they erupted, were hard-fought affairs against increasingly larger confederacies of tribesmen, armed with weapons as effective as those of the Roman army. These wars and in particular the chaos of the 3rd century led to units being destroyed and vexillations failing to return to their home units and becoming independent units. It is out of this period of instability that the army of the late Empire appears.
The change in strategy appears to start with Septimus Severus who for the first time stationed one of his new legions, Legio II Parthica, in Italy as a mobile reserve along with the Praetorian Guard and Urban Cohorts. Gallienus in the mid third century created cavalry vexillations from the cavalry elements of the legions to give him a more mobile strike force. Diocletian makes the last attempt to strengthen the frontier by raising extra legions and auxiliary units, whilst maintaining small field armies for each of his colleagues in the Tetrarchy.
The final system emerges under Constantine. Frontier troops – the limitanei made up of old-style alae and cohorts, supported by the legions plus new style cavalry and infantry auxilia, with field armies the comitatus (from the companions who accompanied the Emperor) consisting of regiments, some derived from the existing legions. Originally the comitatus was under the Emperor’s command, but during the fourth century field armies were created under the command of Dux and Comes within provinces. The British section of the Notitia lists the Comes Britanniarum as commanding six cavalry and three infantry units of the comitatus.
The names and roles of units changed from the invasion when the whole army was a ‘field army’ until the early 5th century when the divisions between the major field army under the control of the Emperor or his senior general, local field armies in provinces and the frontier troops had become established. The names of types of units changed or in some cases old style names were used to describe different troops. Fifth century auxilia were higher grade troops than the auxiliaries of the earlier period and field army units described formally as separate vexillations from the early third century are usually cavalry, however limitanei vexillationes could be infantry. In the historical record many units are kneon by only part of their name, for example Seguntienses, a unit once based at Segontium (Caernarfon) and in the Notitia recorded as part of the field army of Illyricum.
Invasion 43 AD
Praetorians
Singulares
Legio
Alae
Cohors equitata
Cohors peditata
Classis
Mid-2nd century
Praetorians
Singulares
Legio
Alae
Cohors equitata
Cohors peditata
Numerus
Cunea
Classis
Constantine 312 AD
Comitatus
Scholae
Vexillationes
Auxilia
Legio
Limitanei
Legio
Alae
Cohors equitata
Cohors peditata
Numerus
Cunea
Classis
Notitia Dignitatum c 400AD
Comitatus
Scholae
Vexillationes
Auxilia
Legio
Pseudocomitensis
Equites
Other Field Army
Vexillationes
Auxilia
Legio
Pseudocomitensis
Equite
Limitanei
Vexillationes
Auxilia
Legio
Cunei
Milites
Equites
Numerus
Classis
Notes
C onstantine disbanded the Praetorians and replaces them with the Scholae
By the 5th century legions are 1,000 strong, in the early Empire they are around 5,500 strong, when the reduction in size was made is not clear
Numerus and Cunea are small units of around 200 men commanded by legionary centurions. By the 5th century they are also used as general names for regiments and groups of soldiers
Auxilia are high status infantry units and are different from earlier auxilia
Pseudocomitensis are units upgraded by transfer from the limitanei
Units continue to have names that reflect their origins. Equites Dalmatae Branudunenses were raised in what is now Croatia around the middle of the third century and based at the Saxon Shore fort of Branodunum (Brancaster on the Norfolk coast). However sources increasingly use shorter names and many late regiments have titles combining ‘unit’ – Numerus – and their location or origin, for example Numerus Turnacensium, originally based at Tournai and listed in the Notitia as the garrison of Lympne.
Depending on the presumed role of the Saxon Shore forts the navy is either a fighting/reconnaissance force working in conjunction with fort garrisons or part of a system for transporting food and other materials to and from the European mainland via the fortified harbours of the Saxon Shore.