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 ROLE OF THE ARMY
Armies in the Ancient World had a range of functions. Fighting wars was only one and for many soldiers it would have been a rare experience. The Roman army in Britain: acted as a police force, combating minor civil disorders or quelling cattle raids; enforced taxation; and provided skilled administrators and engineers to the provincial governor. The frontier systems should not be thought of as modern frontiers. They were not the equivalent of Iron Curtains between Empire and the barbarians. They were zones that the army patrolled in front off to ensure that allied tribes lived in peace and that lawlessness did not encroach on the province. That lawlessness might be the modern equivalent of a single criminal or rarely an alliance of unfriendly tribes. And when the army did campaign in force it might be because of the tensions caused by competing and proud cultures – native or Roman – or because of an Emperor’s political or personal need for glory.
THE ARMY OF THE EARLY EMPIRE
The army of the first and second centuries had as its core legions. Each approximately 6,000 men strong and recruited from citizens throughout the Empire. The legions fought as heavy infantry, but also provided engineers, cadres of officers and men to assist the government, and officers for the non-citizen troops – the auxilia.
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.
The Praetorian Guard
Of higher status than both the legions and the auxiliaries were the Praetorian Guard. Most of their soldiering was done at Rome as the Emperor’s household troops, although they did accompany him on campaign. The size of the Guard fluctuated, by the second half of the first century it had nine cohorts with 500 men in each. There were also a number of urban cohorts whose role was to maintain order in Rome.
Singulares
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
The total number of legions in the Empire remained at around 30 until the late third century, when the Emperor Diocletian increased their number to over 60. Throughout this period legions were based in frontier provinces where they were able to campaign beyond the Empire. Britain’s garrison fluctuated between three and four legions during the first century, depending on the demands of other provinces, but from the mid 80s AD the number remained at three, though not always the same three, with bases at Caerleon, Chester and York. Assuming an equal number of auxiliaries this suggests a total army strength of between 36,000 and 48,000 men making the British army one of the largest in the Empire
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.
The British legions
Legions like all army units were identified by numbers, but were not numbered sequentially or exclusively and had titles that reflected their history, and helped distinguish them. Full titles are given in the gazetteer with explanations in the glossary. The British legions were:
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.
AUXILIARY REGIMENTS
Auxiliary regiments were either around 500 strong (called quingenaria) or, from the second half of the 1st century, could be around a 1,000 strong (milliaria). Milliaria units were rare – Britain had only one milliaria cavalry unit in its garrison.
Cavalry
Cavalry units known as ala (ala – wing) are thought to have consisted of 16 troops (turmae) with 30 troopers in each if they were quingenaria or if milliaria 32 turmae.
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).
Mixed units
Finally there were mixed infantry/cavalry regiments – cohors equitata. Their organisation is less clear, but are usually assumed to have had six centuries of 80 men and four turmae of 30 troopers, a total strength of 600 men. Cohors equitata milliaria had ten centuries of 80 men and eight turmae of 30troopers, making an establishment size of 1040 plus officers.
Auxiliary units were commanded by tribunes drawn from the equestrian class, second to senators in status, with centurions leading centuries and decurions turmae.
Auxiliary Regiment names
Like the legions, auxiliary units had numbers and names. The most usual part of the name showed where the unit was originally raised. There were for example five cohorts raised in Gaul, Cohors I – V Gallorum. Like the names of legions their names became embroidered with the regiment’s history. Ala Gallorum et Thracum Classiana invicta bis torquata civium Romanorum was raised in Gaul during the reign of Tiberius; it took the title Classiana from the name of its first commander; the addition of a contingent of Thracians gave it the et Thracum; it gained the title invicta, invincible and the honour of a torque twice, hence bis (double) torquata and the grant of citizenship to all of its serving men, civium Romanorum, through its achievements in battle. The first torque was gained possibly during the reigns of the Flavians or Trajan and the second during Trajan or Hadrian’s reign; on both occasions in Britain.
Unit strengths
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.
The Navy
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 OF THE LATE EMPIRE
The structure of late Empire’s army is much less well known. Information in Britain comes principally from archaeology, although since during the late Empire there is a reduction in inscriptions recording building work by the army, the evidence can be confusing. However the Notitia Dignitatum, a list of military and civil officials from the late Empire has survived. The Notitia dates from between the late fourth century and early 5th century. Sadly it omits some locations that from archaeology are known to have been occupied during this period. There is also considerable debate about the period when the British sections were compiled, nevertheless it offers a fascinating insight into the administrative sophistication of the Empire.
Frontiers
The changes in the army were in response to a changing strategic situation. Increasingly from the late first century onwards the boundaries of the Empire become fixed. What once were temporary stop lines become frontiers. Under Domitian frontier defences appear in Germany and Britain – the Gask Ridge on Tayside. Significantly from the Latin for frontier, limes, we gain our word limit.
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 growth of the field army
In time major threats were often met within the Empire although punitive raids continued to be mounted almost until the end of the Western Empire. Often the enemy was too powerful for the army to be strong enough everywhere on the limes to meet the threat. This in turn required standing field armies at nodal points away from the frontier. The old system of creating field armies for major campaigns from vexillations of legionary and auxiliary troops began to be supplemented by small standing field armies accompanying the Emperor. In time this lead to two types of army unit: frontier troops (limitanei) and higher grade field armies (comitatus). It appears that the practice of using vexillations led to the reduction in size of legions in the late Empire and in the duplication of units with the same or similar names that originated from one original.
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.
Types of regiments
The third century changes were matched by an increasing variety of names for regiments. Units become smaller with field army regiments at around 1,000 for infantry and 500 for cavalry and the limitanei at around 300. It is unclear if this happened under Diocletian or Constantine, or indeed whether it was a deliberate change or just the result of downgrading the importance of the limitanei and the creation of field army units from the old legion and auxiliary vexillations. For example it is probable that the Legio Secundani Britones recorded in the Notitia was derived from a vexillation of the II Augusta.
Unit types: Invasion to Notitia
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 Dignitatumc 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
Regimental names in the late army
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.
The Navy of the late Empire
The old-style regional fleets appear to disappear under the late Empire, although the eastern Empire is still able to send invasion forces to Africa, Italy and Spain in the 6th century, presumably using navies similar to the one that delivered the invasion force to Britain almost 500 years before. In Britain it is possible the Classis Britannica may have been split into smaller units attached to the coastal forts and operating in concert with the fort’s garrison as part of the limitanei. Such a unit was presumably Classis Anderetiana that is recorded in the Notitia Dignitatum as being based at Paris, but originated at Pevensey (Anderida).
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.
Copper alloy brooch. Hod Hill brooch, Mackreth type HOD HILL 4.b3. A small bifurcated head is rolled forward to retain pin gear [lost]. An uppermost part of the strip below this bears a single transverse rib. Below this, a nearly square plate has four vertical ribs and small waisted wings. The lower bow is moulded […]
Copper alloy brooch fragment. Cast lower bow and unpierced catch plate from a bow brooch with a narrow rounded bow, possibly a Colchester brooch, Mackreth type C 2. Suggested date: Early Roman, 43-75Length: 26.2mm, Width: 3.3mm, Thickness (bow): 2.7mm, Weight: 2.21gms
Copper alloy coin. Possibly an as indeterminate, Early Roman issue of 43-200, with drilled hole near edge at 10 O’clock[?] obverse.Obverse description: bust probably rightReverse description: possibly a figure.Diameter: 24mm, Weight: 4.82gms, die axis: possibly 12
