Unit Levies after the Batavian Revolt and the Conquest of Northern Britannia

Abstract

In the Early Flavian Period over 30 military units were created or transferred for service in Britannia. Paul Holder maintained that these units arrived with Petillius Cerialis for Vespasian's expansionist plans and connected several new levies to the Batavian Revolt. Considering recent scholarship on Roman responses to revolts and Flavian geopolitics, however, this viewpoint requires revision. The author maintains that these units were transferred throughout the 70s c.e. as opportunities developed organically in Britannia. These newly levied units were not created in response to the Batavian Revolt, but due to the extraordinary and complex circumstances within Rome's northern frontiers after the post-Neronian civil wars. This article concludes with updated histories for the auxiliary units involved.

INTRODUCTION

There is an intimate connection between the Rhineland provinces and Britannia, especially in terms of military transfers between the two regions. This is particularly highlighted by a large sequence of transfers during the 60s and 70s c.e.¹ In the 1980s, Paul Holder argued that several auxilia units levied in Gaul and the Rhineland, or transferred therefrom, in the early 70s were the consequences of the Batavian Revolt (and other movements in Gaul from 68 to 70) and were meant to support the planned expansionist wars of Britain's new governor, Petillius Cerialis in 71 (table 1).² While not every one of these units is attested in Britain, it is plausible that those unattested units were transferred under Domitian to the Danube frontier around the time of his Dacian War, c. 85 (see table 2 and Unit Updates and Arguments).³ Of those transferred to the Danube in the 80s, not all will have served on the war front, some were transferred to places like Raetia to replace units sent to the front or to shore up other frontiers while Domitian's forces engaged enemies elsewhere. Because of how briefly such units served in Britain, less than 20 years in most cases, it is little surprise we lack explicit evidence for them. In this paper, I will propose grounds for widening the date of unit transfers to Britain before presenting a reappraisal of auxilia transfers to Britannia in the early Flavian period. The answer to the date of when these units were levied/transferred has some bearings on how the Flavian emperors planned expansion in Britannia. For example, the tendency in modern scholarship to attribute mass levies or transfers to a single instant comes at a certain interpretive cost. If we allow for the possibility that units arrived over the course of a war or a period of seemingly rapid expansion, then we may see imperial policies in a different light. In the case of Flavian expansion in Britain, the arrival of units over the course of the 70s may align with recent assessments that conquest of the whole island was not conceived in a single instant, namely in 70/1,⁴ but rather that expansion was an organic response as new opportunities and situations developed over the governorships of Cerialis and his successors, Iulius Frontinus and Iulius Agricola. The start of new campaigns in Wales under Frontinus or in southern Scotland during Agricola's third and fourth campaign seasons all represent opportune moments for troop transfers that also conform to the current state of the evidence.

TABLE 1 UNITS ARRIVING IN BRITANNIA IN 71 C.E. (BASED ON HOLDER 1982, 16)

TABLE 2 (POSSIBLE) RECENT TRANSFERS TO BRITANNIA, 70S

New evidence abounds in the decades since Holder's (1982) and Jarrett's (1994) holistic treatments, and it is worth updating their treatments of the late Julio-Claudian and early Flavian garrisons with a list describing which units were raised and/or transferred in this period. However, in keeping with the arguments proposed here, the following table includes both those units that could have arrived with Cerialis in 71 and those that may have arrived over the course of the 70s as situations evolved on the island (table 2). I must emphasise that this list is provisional (on which, see Unit Updates and Arguments). The lack of diplomas prior to 98 and the rarity of firmly datable evidence prevent precision when it comes to the garrison of Britannia in the first century.

CONTEXTS FOR UNIT CREATIONS AND TRANSFERS TO BRITANNIA IN THE 70S

In Holder's formulation, Vespasian conceived early in his reign a grand plan of expansion in Britain to conquer the whole island.⁵ In accordance with this grand scheme, it is believed that several units were levied from Germania and Gallia Belgica to take part in a planned conquest of northern Britain, starting with the governorship of Petillius Cerialis. In his monograph The Roman Army in Britain, Holder would simply state for each recently raised unit from the Rhineland a formula along the following lines: (unit name), ‘raised from (x tribe and tribe's location) after the suppression of the revolt of Civilis this cohort was sent to Britain with Cerialis.’⁶ The geopolitical situation and the garrisoning needs of Britannia were, however, more complex than this presentation.

When Petillius Cerialis was appointed as the governor of Britannia after ending the Batavian Revolt in 70, the garrison of Britannia was depleted from the events of the preceding decade.⁷ Around 66, legio XIV Gemina and eight cohortes Batavorum were withdrawn for Nero's planned campaign in the Caucasus (Tac., Hist. 2.11, 2.27.2, 2.66.1; cf. 1.6.2, 2.17, 2.43.2).⁸ Then, in the chaotic events of 69, 8,000 soldiers from the garrison of Britannia appear among Vitellius’ invasion forces in Italy (Tac., Hist. 2.57.1). Plausibly, these soldiers were brought with Trebellius Maximus when a mutiny caused him to flee Britannia.⁹ Later in the year, during the war with Vespasian, Vitellius ordered further reinforcements from Britannia, which included veterans from legiones II, IX and XX and some picked auxiliaries (Tac., Hist. 2.97.1, 2.100.1, 3.1.2, 3.22). After Vespasian came to power, portions of the garrison, including legio XIV and possibly cohors VI Thracum, the former having just returned to Britain with Bolanus in late spring of 69 (Tac., Hist. 2.66),¹⁰ were sent to help Cerialis end the Batavian revolt in 70 (Tac., Hist. 4.68.4). In summary, Britain's garrison was short of bodies after the civil wars, given the transfers of men to other theatres and their subsequent losses. Considering this situation, Cerialis brought several units to Britannia that had aided him in returning the Rhineland to Roman order.¹¹

Furthermore, it was probable that the garrison required replenishment to manage the Brigantes, where Cartimandua's client-state was usurped during Vettius Bolanus’ governorship (Tac., Agr. 17.1; Hist. 3.45). It is important to bear in mind that Petillius Cerialis’ campaigns against the Brigantes were not a war of conquest/expansion. Cartimandua was a client-ruler allied to Rome since at least 51 (Tac., Ann. 12.36, 12.40) and, in principle, her kingdom would already have been an indirect extension of Roman suzerainty. Rather, between Venutius’ coup in 69 and the end of Cerialis’ campaigns in 73 (Tac., Hist. 3.45; Agr. 17), what we are witnessing is not a war of conquest, but a Brigantian uprising against Cartimandua and her Roman overlords that ultimately results in Rome's direct rule over the tribe.¹² Cerialis’ endeavours here must then be viewed as a circumstantial incorporation of a tribe directly into the empire, rather than a planned effort to begin conquering and incorporating the rest of the island.

If we break into two phases Rome's response to Venutius overthrowing Cartimandua, the immediate response of Bolanus and the planned response of Cerialis once the civil wars ended, then we may begin to contextualise why some of these units were raised and others were transferred. A few scholars have noted that it was common for Roman generals to respond quickly to the outbreak of revolts and send whatever available forces they had to hand before the revolt could spread throughout a province or to adjacent provinces. While it was risky to engage in such a strategy, it reveals how much Roman commanders emphasised seeking ‘a swift solution of local tensions … even if [an encounter with rebels] entailed numerical inferiority.’¹³ This is exactly what happened in Tacitus’ brief notice of Bolanus’ approach to the situation (Tac., Hist. 3.45.2). Clearly the governor could not stamp out the unrest amongst the Brigantes quickly, especially with his reduced garrison. The Brigantes were a large and powerful tribe, and it seems that Bolanus met them in battle multiple times (et cohortes alaeque nostrae variis proeliis) but failed to bring the tribe back to order (Tac., Hist. 3.45.2; cf. Stat., Silv. 5.2.144–9). Because Rome often managed to handle revolts quickly with whatever forces there were to hand, it is relatively rare that new levies were required to prosecute a mass uprising. In this case, we must look to the Great Illyrian Revolt of 6–9 and the Varian Disaster in 9 for Roman precedents of raising new units to help put down recalcitrant populations.¹⁴ In both situations, the state created the units after initial local efforts to put down rebels failed or were ineffective. The tight timeline between the end of the revolts in the Rhineland and the start of Cerialis’ wars in Britain have muddled our perception of the cause of so many units being levied in so short a period. If we are to view Cerialis as levying all these units for his campaigns, then we must see the mass levy as an emergency because the stripped garrison of Britannia could not deal with the situation as it stood.

What we witness in the Rhineland levies of the early Flavian period are not the (direct) consequences of the Batavian Revolt (Holder's formula above seems to imply that the transfers and new levies were a form of punishment for their involvement), but rather the exigencies required by the complex circumstances within the northern frontiers of the Roman Empire in the wake of post-Neronian civil wars. Once we recognise the fact that the revolt was intimately intertwined with the politics of the civil wars, making it difficult to define Civilis’ movement as purely an indigenous revolt, it becomes rather questionable to see the levies as a form of punishment.¹⁵ It is not entirely clear as to which tribes yielded new units after the revolt, which should raise doubts about connecting these new units directly to a given tribe's involvements in the Batavian Revolt. Namely, new units do not appear drawn from the staunchest participants in the revolt, the Batavians and Cannanefates (see Unit Updates and Arguments below on the Batavi).¹⁶ New units appear indiscriminately across tribes in the region, however, regardless of the extent to which each tribe participated in either side of the conflict (see Unit Updates and Arguments, especially the Morini, Menapii and to a degree the Baetasii). The indiscriminate nature of recruitment in this period may instead be an indication that units were created on an ad hoc basis as opportunities for expansion gradually developed in Britannia from 71 to 83.

While some units could have been created for service in Britannia during Cerialis’ governorship alongside those pre-existing units transferred in 71, others were surely raised in the contexts of Frontinus’ and Agricola's wars of expansion in Wales and Scotland. Moreover, it is known that Rome often raised new units in preparation for new wars, either to serve in the campaigns or to replace units transferred to the war theatre. In fact, recruitment during the Principate was heaviest in the lead-up to fresh wars or over the course of ongoing wars, because Roman decision-makers kept units and members within their ranks at minimal levels during times of peace to reduce the costs of maintaining Rome's military.¹⁷ By the end of his governorship, Petillius Cerialis had established a fort at York at the edges of Brigantian territory, forts as far north as Carlisle in the territory of the Carvetii and a military installation at Chester, predating the legionary camp started in 74.¹⁸ The establishment of the fort at Carlisle suggests that Petillius Cerialis had campaigned beyond that point too. Venutius, the Brigantian usurper, may have had supporters to the north of the Brigantian Confederation (Tac., Hist. 3.45), which pulled Rome into southern Scotland, creating opportunities for future Roman expansion. One possible hint of this activity lies at the Bankfoot temporary camps at Dalswinton, which Hanson et al. speculate might belong to a pre-Agricolan context, perhaps Cerialis’ or Frontinus’ campaigns. Furthermore, Tacitus’ phrasing ‘multae civitates’ in Agricola's second season implies that Agricola faced populations in addition to the Brigantes (Agr. 20.2). Given that Agricola only meets unfamiliar tribes in his third season, then Agricola's predecessors must have operated beyond the Brigantes too.¹⁹

Whereas Petillius Cerialis’ governorship of Britain was largely centred on ending an indigenous revolt and establishing direct Roman control over the Brigantes, Frontinus’ campaigns were expansionist efforts to conquer Wales successfully once and for all. This was a planned campaign, as evidenced by Cerialis beginning construction of a new legionary camp for legio II Augusta at Caerleon in winter 73/4; the governor was already shifting units to a new war front on the eve of Frontinus’ arrival and campaigns, with legio II Augusta moving from Gloucester. As Gambash reminds us, the Silures were a nearly constant enemy to Rome for thirty years, dating back to the tribe sheltering Caratacus before Ostorius Scapula invaded southern Wales in the late 40s.²⁰ Iulius Frontinus’ governorship, then may constitute a likely scenario for when several of our units were levied. In terms of newly levied auxiliary forces in the 70s, if we assume that the soldiers receiving privileges in the British constitutions of 98 had served their 25-year terms in a single unit (CIL 16.43; AE 2014, 1627), then some units could have been raised towards the end of Cerialis’ governorship, possibly in relation to the Flavian census of 73/4 and/or the planned campaigns in Wales to be conducted by Sextus Iulius Frontinus. In this regard, the cohortes I–V Lingonum may belong in this category, where they could have been raised in 73 and shipped off to Britannia with Frontinus at the beginning of his governorship (see Unit Updates and Arguments). Meanwhile others, such as cohortes I Baetasiorium, I Cugernorum, I Morinorum and I Menapiorum, may have been created at this time or a few years later (see Unit Updates and Arguments). As Holder has shown, Cerialis already took numerous reinforcements to the island, even if we discount newly levied units, including legio II Adiutrix and some auxiliary units recently serving in the Rhineland. It may therefore not have been necessary for him to raise more units for his campaigns against the Brigantes (see table 2; Unit Updates and Arguments/Transferred 71). We cannot, however, press this point, given how little we know about these campaigns.²¹

In terms of the relationship between the global census of Vespasian and Titus of 73/4 and the levying of units for service in Britannia, it is worthwhile to consider how provincial censuses provide excellent opportunities for levying soldiers. I have argued elsewhere that the Roman state could utilise censuses and the information derived from them to assess and mobilise the manpower of provinces for upcoming major campaigns, such as Iulius Frontinus’ intended campaigns in Wales. I also suggest that this was a feature of Roman administration which gradually disappeared by the reign of Hadrian.²² To summarise these arguments, the information collected from census operations allowed Rome to take into account the obligations of individual communities towards Rome; to assess the capabilities of individual communities to support war efforts; and to determine the (tax, auxilia quotas and/or military supply) burdens for each community in the lead-up to campaigns. Now, while the census of Gallia Belgica conducted by P. Babullius Salluvius at this time was surely part of the general census of Vespasian and Titus (AE 1975, 251)²³ (a census operation aimed primarily at refilling the state's coffers after years of Neronian heavy spending and the high cost and loss of tax income from the civil wars of 68–9), it does not mean that the census conducted in Gallia Belgica could not simultaneously serve military needs. As seen above, the garrison of Britannia desperately needed fresh recruits after several transfers out of the province during the civil wars, and there was an additional demand for troops to support the planned imperial expansions during the governorship of Iulius Frontinus.

Although Tacitus only mentions Frontinus’ governorship briefly and limits his actions to the Silures of southern Wales (Tac., Agr. 17.2), modern scholars give him credit for more extensive campaigning in Wales and continued efforts in northern England. For example, Birley interpreted Tacitus’ phrase ‘took up and sustained the burden’ (subiit sustinuitque molem) at Agr. 17.2 to mean that Frontinus continued Cerialis’ operations in the north.²⁴ Meanwhile, concerning Frontinus’ Welsh campaigns, Gambash has recently played down Agricola's successes in northern Wales early in his governorship. Pointing out that Agricola arrived in Britain in midsummer and met no opposition until the isle of Mona, he suggests that the conquest of northern Wales was nearly complete by the beginning of his governorship. The fact that Tacitus mentions an ala in Ordovician territory when his successor Agricola arrived perhaps points to Frontinus coming to terms with at least a portion of this tribe (Tac., Agr. 18.1).²⁵

But we may go further by utilising archaeological advances in Roman Wales to augment conceptions of what Frontinus had achieved during his governorship. Prior to Frontinus’ arrival, Cerialis had already begun breaking ground on a new legionary camp at Caerleon, which shows that Rome already leveraged some control in Silurian territory. Once Frontinus was on the ground, early Flavian campaign bases such as those at Caersws 1, Llandeilo 1 and Llandovery (Phase 1) reveal how thoroughly he had penetrated both Silurian territory and central Wales. Burnham and Davies contend that these forts accommodated field forces ‘in the early stages of taking territory; as such they represent the transition from a mobile force to an army of occupation, forts serving as hiberna or aestiva turned into more permanent bases.’²⁶ Furthermore, the early Flavian forts at Carmarthen, on the site of the Demetae's later civitas centre, and Loughor reveal that Frontinus had been active in south-west Wales as well. Meanwhile, the campaign fort at Llanfor, which predates the Caer Gai fort (founded c. 75–80), unveils how far Frontinus had advanced into Ordovician territory during his governorship.²⁷

Back in England, it is also plausible that Frontinus was responsible for moving legio II Adiutrix from Lincoln to Chester (or at least beginning to create its new base in 74) along the frontier of northern Wales and north-western England.²⁸ This camp would have been useful for monitoring the populations of northern Wales and north-western England as well as forming a base from which to conduct operations in both regions. There was a military installation active at Chester prior to this point, from which Frontinus could have continued efforts in north-western England during his governorship. It is very unlikely that Frontinus would have ignored the north of England and he surely continued to deploy forces at a minimum to consolidate control over Bolanus’ and Cerialis’ gains.²⁹ Indeed, it remains quite possible that Rome required continued activity against Brigantian rebels and/or their allies. Cartimandua's client-state likely only had nominal control over the Pennines and continued campaigns were surely required to bring these outlying populations under Roman control. To summarise, we may quote Shotter's assertion that Tacitus’ ‘omissions [on Frontinus’ activities beyond the Silures] have the effect of enhancing the significance of the work of his father-in-law, “promoting” it from the consolidation which much of it now appears to have been.’³⁰

Finally, Domitian's accession provided Agricola with an opportunity to pursue Roman expansion beyond the Tay frontier into north-eastern Scotland. Domitian's desire for military glory, which is something he lacked compared to his brother and father, is the likely driving force for Agricola's final campaigns in northern Scotland, probably occurring simultaneously with the emperor's own activities in the Chattan War. Agricola's first years as governor were spent largely completing ongoing imperial campaigns and consolidating recent gains, which would have required few, if any, additional units to the garrison.³¹ It is not until Agricola's third campaign season, 79/80, that he engages new populations when he advanced as far north as the Tay (Tac., Agr. 22.1–4; Cass. Dio 66.20). Strategic withdrawals of some early forts and deploying vexillations from the garrison of Wales may have reduced the need for new units at this time for Agricola's efforts.³² But, after 81 until the battle of Mons Graupius,³³ Agricola's rapid campaigns north could have seen his garrison augmented by new arrivals such as cohors Frisiavonum and ala II Asturum (see Unit Updates and Arguments for further possibilities). As such, we may divide new arrivals into those who likely arrived with Cerialis to replace units removed during the 60s – with a few extra perhaps to handle the Brigantes; those who arrived with or during Frontinus’ governorship for his campaigns in Wales and northern England; and finally those who arrived in 80/81 during the latter years of Agricola's governorship.

UNIT UPDATES AND ARGUMENTS

A reappraisal of the Flavian-era garrison in Britannia is long overdue. As with previous efforts to appraise the garrison of Britannia, there remains a significant amount of guesswork in establishing the shape of the Flavian garrison, especially in determining when various units arrived on its shores, despite continued discovery of new inscriptions and archaeological advances. As such, table 2 above and the justifications below are to an extent speculative and will require revision as our knowledge of the Flavian garrison continues to advance. As far as I can carry the evidence, I have ventured to divide the units into periods when they most probably arrived in Britain. This reflects the thrust of the arguments above, namely that auxilia units arrived throughout the 70s rather than in a single transfer. Where some units were previously ascribed with a transfer to Britannia under Cerialis, at times I suggest we accept a broader transfer date based on the available evidence for each unit (until new evidence narrows that date down).

BATAVIAN UNITS POST REVOLT

There is a significant amount of guesswork involved in the nature and history of the Batavian units in the final decades of the first century. Because Tacitus’ Histories cuts off before we learn of Civilis’ and the Batavian units’ fates (Hist. 5.24–26), it is uncertain exactly how many units survived the revolt or when certain units became milliary (i.e. double the size of the notional 480 men of the standard unit). It is my opinion that we should disregard the popular notion in which the existing Batavian units were disbanded and replaced by eight new cohortes Batavorum and maybe one ala Batavorum as a result of their involvement in Civilis’ Revolt.³⁴ Since Rome's aim in handling revolts was a return to peaceful routine,³⁵ it is more likely that Petillius Cerialis’ terms to Iulius Civilis stipulated that many of the soldiers serving in the recalcitrant units would return to the Roman army with the exception of the ringleaders and those nearing the end of service. This type of response has precedence with the legionary mutinies in the Rhineland and Pannonia after Augustus’ death in 14 (Tac., Ann. 1.16–49). Additionally, it is worthwhile to note that Cerialis had dealt leniently with soldiers who had defected during the Batavian Revolt (Tac., Hist. 4.72).

Furthermore, Spaul rightly points out that not all Batavians were culpable in the revolt; rebellions never encapsulate whole populations. Some, if not many, soldiers within the rebel ranks followed their leaders without necessarily being wholehearted participants in the revolt (see, for instance, Tac., Hist. 4.55–60.). In fact, prominent Batavians aided Rome in the fight against their compatriots, such as Iulius Briganticus, Civilis’ nephew and the commander of the ala Singularium founded by Vitellius, and Claudius Labeo, a man who initially joined the rebellion but defected and waged a guerrilla war against Civilis’ allies.³⁶ While we simply do not know what terms Petillius Cerialis dictated to Iulius Civilis, or the Batavians more generally, Tacitus’ account in the Germania suggests that the tribe did not face harsh reprisals (Tac., Germ. 29). Batavian élites continued to have opportunities to lead Batavian units into the second century, among whom the most famous is Flavius Cerialis, who commanded cohors VIIII Batavorum in the late first century at Vindolanda.³⁷

We must also consider that, demographically, the Batavian population could not have carried the wholesale fresh levying of nine new Batavian units. Research over the past forty years has continually emphasised that military service was a heavy burden in the long term on the Batavian people. With roughly 5,000 to 6,000 men serving in nine auxilia units, in addition to those in the fleets, the Germani corporis custodes and legions,³⁸ out of a total population size of probably 30,000 to 40,000 individuals means that roughly two-thirds of military-aged men were actively serving Rome at any given time. Estimates suggest that every household with men of military age had at least one member in active service.³⁹ The only way that we can imagine the complete dismissal and replacement of the Julio-Claudian Batavian units is if the recruits for the new ones derived largely from neighbouring populations. While neighbouring populations increasingly served in these units into the second century,⁴⁰ two arguments speak against the likelihood of this proposal. One, it is difficult to believe that those who were involved in the revolt would be allowed to return to their homes where could they be a nuisance to the Rhineland after forces dispersed (although admittedly the new legionary camp at Nijmegen would have been a good deterrent). Two, given the fact that many of the Batavi's neighbours were now subjected to levies of their own ‘national’ units, the idea that these populations could have carried more than half of the burden of supplying nine Batavian units in addition to their own auxilia units is unlikely. Therefore, it is more probable that Rome applied a pragmatic approach to the situation and maintained most of those already serving in the units.

TRANSFERRED 71

Ala Petriana was most certainly in the Rhineland in the Julio-Claudian period (CIL 13.6820: Mainz) before fighting for Vitellius in the invasion of Italy (Tac., Hist. 1.70). It probably landed in Britain with Cerialis, though one cannot rule out a slightly later date given that it is first attested at Corbridge (RIB 1172: 80–98). Hodgson has recently proposed that ala Petriana was milliary already by c. 86 and could have been garrisoned at Dalswinton phase II based on the length and number of barracks. The strategic grounds for Hodgson's suggestion are reasonable, namely that it was a key site on the front line in the north for the late first century. However, the lack of a milliaria sign on the constitution of 98 is a potential issue (CIL 16.43). While Spaul hypothesised that the lack of a milliaria sign was simply a scribal error, it remains possible that the unit could have shared the camp with another unit, if it was garrisoned at Dalswinton. Maxfield suggests the unit received the distinction torquata between 98 and 122 (CIL 16.43: 98 Diploma; Tab. Vindol. 2.258: 97–105; CIL 16.69, RMD 5.360: 122 Diplomas).⁴¹

Ala Sebosiana appears to have served in the Rhineland before 68 (CIL 13.6236, CIL 13.11709: Worms; BRGK 17 (1927) 216: Mainz), after which it fought against the Flavian invasion of northern Italy in 70 at Forum Alieni (Tac., Hist. 3.6). Its appearance on Tab. Luguval. 44 at Carlisle, 77–84, makes it a likely candidate for moving with Cerialis to Britain in 71 (= AE 1998, 852). Tomlin notes that while this tablet does not guarantee ala Sebosiana was stationed at Carlisle under Agricola, it is his opinion that it was likely.⁴²

Eight Batavian cohorts had served in Britannia during the later Julio-Claudian period, leaving around 66 with Legio XIV Gemina (Tac., Hist. 1.6.2, 1.59). These units then served Rome during the civil wars before ultimately joining Civilis’ cause (Tac., Hist. 2.27.2, 4.15, 4.19ff.). After the Batavian Revolt, Cohors I Batavorum returned to Britain, probably under Cerialis, where it later likely participated in the battle of Mons Graupius (Tac., Agr. 36). It appears on a recently discovered constitution for Britannia of 98, where it remains in province into the second century (AE 2014, 1627: lacking milliaria and pia fidelis).⁴³

Cohors II Batavorum also returned to Britain after the civil wars, probably with Petillius Cerialis. It could feasibly have been among the four Batavian units at Mons Graupius under Agricola (Tac., Agr. 36), before leaving Britain for the continent shortly thereafter, probably around 85. Cohors II was definitely in Pannonia by 98, when it appears on a constitution and was stationed at Klosterneuburg (CIL 16.42). The unit also served in a Dacian War as it was attested on the Adamclisi Monument, dating to the reign either of Domitian or Trajan.⁴⁴

Cohors III Batavorum left Britain by 107 when it appears on a constitution for Raetia (CIL 16.55). Surely it had returned to Britain at the same time as cohorts I and II, probably with Cerialis. Cohors III is attested on two Vindolanda tablets and is often listed as one of the likely Batavian units at Mons Graupius (Tac., Agr. 36; Tab. Vindol. 2.263, 311, 860 (?): 97–105). The likeliest context for it leaving Britain was Trajan's Second Dacian War.⁴⁵

Cohors IX Batavorum left Britain between 105 and 116 for Raetia, probably at the same time as cohors III Batavorum (RMD 3.155: 116. Cf. AE 2002, 1083 = CIL 3.11918: Weißenburg, 104/106–120). This would mean that cohors IX was among the units transferred around the time of Trajan's Second Dacian War and its aftermath. The unit had surely arrived in Britannia at the same time as cohorts I, II and III, and is frequently counted among the four Batavian units which fought at Mons Graupius with Agricola (Tac., Agr. 36). Later, cohors IX was stationed at Vindolanda during the fort's second and third occupation phases (i.e. Tab. Vindol. 2.242, 2.263, 3.574: 95–105). During its stay at Vindolanda, the unit appears on a constitution of 98 (AE 2014, 1627).⁴⁶

Cohors I Tungrorum probably existed prior to the civil wars, with two Tungrian cohorts forming part of Fabius Valens’ army (Tac., Hist. 2.14–15).⁴⁷ It is thought to have travelled with legio II Adiutrix to Britain from the lower Rhineland in 71. It is next attested at Mons Graupius and at the phase 1 fort of Vindolanda (Tac., Agr. 36: 83); Tab. Vindol. 2.154+add.; Tab. Vindol. 3.857: 85–92).⁴⁸

Cohors II Tungrorum likewise probably existed prior to 68 and is assumed to have come to Britain during the 70s. Scholars generally assume that it was also present at Mons Graupius with cohors I Tungrorum. The regiment does not appear on early constitutions from Britain, but a vexillation of cohors II is attested on diploma from Raetia and Noricum in the second century. Did the unit, or at least part of it, leave Britain shortly after Agricola's governorship?⁴⁹

After being levied by Galba (Tac., Hist. 4.33–4), Cohors II Vasconum found itself among the forces putting down the Batavian Revolt. It has been suggested that the unit arrived with Cerialis since it was present with the general on the lower Rhine immediately before his arrival in Britain (RIB 2401.2: 105).⁵⁰ Jarrett proposed that the ignotus of CIL 2.1086 likely served as its prefect during the unit's transfer to Britannia, but questions abound on the authenticity and date of the inscription.⁵¹

ARRIVALS IN 70S

Alföldy suggested Ala I Tungrorum existed prior to the Year of the Four Emperors, even suggesting it may have arrived on the island under Claudius or Nero. There is an inscription dating from 20 to 40 that may attest to the presence of an ala Tungrorum outside Salona, which may be the same unit later attested in Britain (AE 1994, 1356 = AE 2002, 1118). A constitution of 98 is the first evidence of it in Britannia (CIL 16.43). As such, most scholars contend that I Tungrorum only arrived after the Batavian Revolt with Cerialis. RIB 2140 suggests that the unit was later stationed at Mumrills on the Antonine Wall, possibly serving as its first garrison.⁵²

Cohors I Baetasiorium first appears on a constitution from Britannia in 103 (CIL 16.48 = RIB 2401.1: Caerleon), which suggests that the unit was raised by 78 at the latest (based on a 25-year term of service for the first recruits). Baetasii played a role in the Batavian Revolt, first serving as a tumultuaria manus (an irregular force) under Claudius Labeo, but then defecting to Iulius Civilis (Tac., Hist. 4.56, 4.66). It is most likely that the formal tribal contingent was created between 70/71 and 78 and this unit is unlikely related to the earlier irregular force. This cohort could have arrived with Cerialis, as presented by Holder and Spaul, or created using information derived from Vespasian's census of 73/4 to aid Frontinus’ Welsh campaigns or even later still to support Agricola's ventures. All three options must remain open possibilities at this time. Cohors I may have served early on at Manchester, but the inscription there could also belong to a Severan context (RIB 581 = CIL 7.216).⁵³

Just like the Baetasian unit, Cohors I Cugernorum first appears on a constitution of 103 (CIL 16.48 = RIB 2401.1). Scholars typically assert that Cerialis levied it for his campaigns in northern England, though Spaul suggests it may have been created by Trajan if the members cashiered in 103 were the training corps transferred from other units. Given the date of its first attestation, we must also consider it was levied for Frontinus’ or Agricola's campaigns. The unit appears to have received its full title, cohors I Ulpia Traiana Cugernorum c.R., between 103 and 117, most likely after briefly serving in Trajan's Second Dacian War, returning to Britain thereafter (CIL 16.69, RMD 5.360: both 122 c.e.; AE 2005, 678).⁵⁴

There were one or two Cohortes I Hispanorum active in Britannia in this period, appearing on constitutions of 98 (CIL 16.43), 103 (RIB 2401.1) and 105 (CIL 16.51). Holder maintains that one was levied in Hispania in the Augustan era and served in Galatia before ultimately arriving under Cerialis. Jarrett backed Holder's claim by pointing out that the names appearing on a Flavian inscription at Ardoch, Ammonius and Damio are of eastern origin (RIB 2213). This unit then served at Maryport, maybe c. 98, as the P. Cornelius P. f. Gal. Ur[---] on RIB 821 later appears on a diploma dating to 13 March 101 (AE 2013, 2192). To summarise, at least one cohors I Hispanorum probably arrived in Britannia in the 70s, perhaps having left Galatia during the Year of the Four Emperors.⁵⁵

There is a series of five Cohortes Lingonum that were created in the early Flavian period. The first attestation for any Lingonian cohort is a constitution of 98 (CIL 16.43). Holder maintains that Cerialis raised all five cohorts after the suppression of the Batavian Revolt and shipped them off to Britannia.⁵⁶ Meanwhile, Roger Tomlin has recently proposed that these five units were already in existence by the end of the Julio-Claudian era, given the presence of a Lingonian, Rogatus, on a Bloomberg tablet (WT55 = Tab. Lond. Bloomberg 55 = AE 2016, 950). He then reinforces this hypothesis by pointing to the earlier attestation for cohors VI Nerviorum and cohors I Vangionum, both viewed previously as Cerialian creations (see In Britain Before 71, below). While it is possible that this Rogatus was a soldier, there is no evidence that Lingonian units were in existence at that time. As Tomlin rightly points out, Lingones were already serving in the Roman army at this time, but they were not necessarily doing so in a Lingonian cohort (CIL 13.7034: Mainz).⁵⁷ The likeliest context for their creation, then, should be the years between 70 and 73. However, rather than being a punishment for some of its members’ active participation in the Rhineland revolts (Tac., Hist. 4.55, 4.67, 4.77), their levy may be a voluntary show of loyalty to the Roman noble who accepted their surrender. It is worth noting that when the Lingonian civil population surrendered without a fight, they had provided Frontinus with 70,000 warriors, which were possibly used to help quash Civilis’ forces (Frontin., Str. 4.3.14). It is then tempting to hypothesise that Frontinus utilised his newfound relationship with the tribe for recruitment efforts prior to the start of his governorship of Britain in 74. The Lingones had previously sided with Vitellius when he was elevated to the purple because Galba had punished them for helping end Vindex’ revolt, his ally (Tac., Hist. 1.53, cf. 1.8). The participation of some Lingones in Civilis’ uprising may then be related to a fear of Vespasianic reprisals, much like those enacted by Galba. Alternatively, their surrender to Frontinus had changed the tribe's relationship to Rome and their creation was the result of a service quota imposed at the time of Vespasian's census of 73/4, given that twenty-five years later is the early firm attestation for any cohors Lingonum (CIL 16.43: 98).

Even though Cohors I Lingonum equitata only first appears in 105 (CIL 16.51), it is likely that all five units were raised at the same moment, surely sometime between 70 and 73.⁵⁸ Cohors II Lingonum first appears on constitutions for Britannia in 98 and 105 (CIL 16.43, 51). It is uncertain where this unit had served early on in Britain.⁵⁹ Likewise, where Cohors III Lingonum served is entirely unknown. The two second-century inscriptions for prefects offer no aid (CIL 11.5959; ILG 643). The earliest evidence for this unit is constitutions of Britannia for 98/114 and 103 (RMD 3.151; CIL 16.48).⁶⁰ Cohors IIII Lingonum is now first attested on a constitution of Britannia in 98 (AE 2014, 1627; cf. RMD 3.151: 98/114).⁶¹

Cohors I Morinorum appears on an honorary inscription of C. Mulvius Offilius Rest[it]utus, with a proposed date for his military career to c. 70 to 78 (AE 1972, 148 = PME M 71) as well as a constitution of 103 (RIB 2401.1 = CIL 16.48). Alföldy had counted this unit among those created to serve in Britannia under Claudius or Nero, but there is no reason to suppose its existence before the Flavian era. It is more likely that, as Holder argues, it was created at the beginning of Cerialis’ governorship. Given the dating for Offilius’ career, he could very well have been its first prefect. Since the only other early documentation of this unit is the constitution of 103, then a levy as late as 78 remains plausible. As such we should consider the possibility that I Morinorum was levied to support Frontinus’ operations, either in Wales or the northern frontier.⁶² In turn, Offilius’ inscription should receive a wider dating for his military career to 70 to 100, since the only dating restrictions are that two of the units he commanded were created in the early 70s. Furthermore, a date of c. 70 to 78 presupposes a rapid promotion through the military cursus, which is not particularly common.

Cohortes Nerviorum

Until very recently there was a debate on when the series of six Nervian cohorts was created, whether that was under the Julio-Claudians or Vespasian. Tacitus mentions cohortes Nerviorum in Vitellius’ army in 69, terminology which implies they were regular auxiliary forces (Tac., Hist. 4.33).⁶³ Prior to 2016, there was only one probable piece of evidence for Nervian units in the Julio-Claudian period.⁶⁴ A tablet uncovered during the Bloomberg dig in London, however, revealed that the whole series existed since at least the 60s, because it mentions cohors VI Nerviorum (Tab. Lond. Bloomberg 33 = AE 2016, 932).⁶⁵ Since this tablet attests to the existence of a cohors VI Nerviorum in the Julio-Claudian period, then we should accept units I–V also existed from 61 at the latest, with perhaps some in the series only leaving the Rhineland after 71. This casts doubts on the notion that the series was raised for service in Britannia. Instead, Nervian cohorts probably initially served in the Rhineland like so many other Belgic and Germanic regiments.

Cohors I Nerviorum is first securely attested in Britannia on a constitution of 105 (RIB 2401.2). There is a shrine with an inscription of the unit at Caer Gai (RIB 418), a site founded 75/80 and occupied until c. 140. It is impossible to state whether cohors I was the first occupant of Caer Gai or that it was stationed there during the fort's primary occupation phase (pre-100), but it is likely that the regiment was transferred to Britain at some point in the 70s. There is no attestation of cohors I Nerviorum after 105; whether this is because it ceases to exist or because it becomes I Nerviana is a matter of debate.⁶⁶

Cohors II Nerviorum's early history in Britain is only confirmed by diplomas. It first appears on constitutions for 98 (CIL 16.43) and 96/108 (RMD 2.83). Like cohors I, this regiment most likely arrived in Britannia with Cerialis, Frontinus, or Agricola.⁶⁷

The history of Cohors III Nerviorum is largely still a mystery, with it only being first attested on constitutions for 122 (CIL 16.69, RMD 5.360). There are possible references to the unit at Marypoint and Vindolanda, but alternative readings are feasible. A lead seal found at Newstead, however, could attest to the unit's presence there at some point between the governorship of Agricola and c. 180 – though it may not have been garrisoned there. Since cohors VI was in existence since at least the 60s, it is unlikely that cohors III Nerviorum was created at a later date (unless one believes there was more than one series of Nervian units – an improbability). If we hesitantly accept that most of the cohortes Nerviorum transferred from the Rhineland to Britannia at the same time, then cohors III probably arrived in the 70s – though, at present, a later transfer to the island must remain feasible.⁶⁸

Cohors IV Nerviorum is also a poorly understood unit. It is only attested on diplomas, the first being a constitution of 135 (RIB 2401.8). Like cohors III, such a late firm attestation for cohors IV could point to a later transfer to Britannia. But, if the whole series transferred in one instance, as is frequently asserted, then cohors IV probably arrived at some point in the 70s during any of the early Flavian campaigns.⁶⁹

LATER ARRIVALS?

Ala II Asturum was created under the reigns of Augustus or Tiberius and served in Pannonia at some point prior to its transfer to Britannia before 122 when it is attested on constitutions (CIL 16.69; RMD 5.360). Scholarship is divided on when the unit served in Pannonia, and this has bearings on when the unit likely arrived in Britannia. For Holder, ala II served in Pannonia during the reigns of Claudius and Nero before finding its way to the Rhineland during the civil wars of 69, where it was among four cavalry regiments from Pannonia that helped put down the Batavian Revolt (the others are ala Claudia nova, ala Moesica and ala Scubulorum). From there he proposes that the regiment was among the several pre-existing units serving in the Rhineland that transferred to Britannia with Cerialis. Spaul argued that the unit was created in the Claudian era for service in Pannonia and it may have arrived in Britannia with Iulius Agricola. Meanwhile, Lőrincz had maintained that the unit arrived in Pannonia from the Rhineland at the beginning of Vespasian's reign, where he proposed it was stationed at Intercisa from 70 to 92, after which it was transferred to Britannia. The major issue is the dating for the regiment at Intercisa, with Holder providing a Neronian date while Lőrincz favoured an early Flavian date for RIU 1207 and 1216. What is incontrovertible, though, is that ala II Asturum appears on a constitution of Pannonia in 61 (RMD 4.202). Furthermore, II Asturum does not appear on Pannonian constitutions of the 80s nor on Germania constitutions of the 70s to 90s, which could mean that this unit was in Britannia by 80. Holder is correct in stating that after 82/83 the trend is for regiments leaving Britannia, not arriving. As such, I would like to propose that the Intercisa inscriptions, and CIL 3.14349 (Aquincum), date from c. 60 to c. 79 and that the unit had transferred straight to Britannia from Pannonia during the governorships of Frontinus or Agricola. Ribchester is where the unit was probably stationed in the late first or early second century (RIB 586). In summation, the suggestion that ala II Asturum arrived with Cerialis makes sense, but it is by no means a certainty.⁷⁰

Raised from the Frisiavones of Germania Inferior, Cohors I Frisiavonum was levied by 80 based on a constitution of 105 for Britannia (RIB 2401.2). The unit was either involved in the building of Melandra Castle (RIB 279) and Manchester (RIB 577–579) forts in the late 70s or in the second-century rebuilding of the forts. While Holder maintains Cerialis created the unit after the Batavian Revolt and shipped it off to Britannia in 71, it may be more prudent to see this unit's creation in an Agricolan context to secure Brigantian territory while he campaigned further afield.⁷¹

Cohors I Menapiorum is first attested on a Trajanic constitution of Britannia dating to 98/114 (RMD 3.151). Alföldy suggested this unit could have been levied in the Julio-Claudian period for service in Britannia, while Holder prefers a post Batavian Revolt context. There is, however, no certain evidence until the aforementioned diploma. Either cohors I Menapiorum or Morinorum may be recorded on a leather offcut dating to 97–103 at Vindolanda (RIB 2245.1), though neither was stationed there. The regiment could have been established as late as 73 to 89 depending on the date of RMD 3.151. Cohors I Menapiorum and cohors I Morinorum were likely created at the same time for coastal or naval operations on the island.⁷²

Cohors I Sunucorum first appears on constitutions of 122 in Britannia (CIL 16.69; AE 2008, 800) and on a pre-Hadrianic graffito at Holt (AE 1914, 293: c. 90–c. 117). Civilis had raised a cohort from the tribe's youths (Tac., Hist. 4.66: occupatisque Sunucis et iuventute eorum per cohortis composita), but it is uncertain whether this rebel unit is the same as the one that later served in Britannia.⁷³ In terms of arrival date, Alföldy supposed the unit was already in Britain in the Julio-Claudian period, whereas Holder contends that it was levied after the Batavian Revolt and arrived with Cerialis. Given the late date for the unit's first attestation, I prefer Jarrett's proposal that the unit was created as late as the first years of Trajan's reign, but recognise it remains possible that cohors I Sunucorum was established or reconstituted after the Batavian Revolt and shipped off to Britannia with Petillius Cerialis.⁷⁴

POSSIBLY IN BRITAIN BEFORE 71

There was an Ala Agrippiana in the upper Rhineland during the early Principate (CIL 13.6235: Worms, c. 20-41). Given that the unit does not appear on any constitutions prior to 122 (CIL 16.69; RMD 5.360; AE 2008, 800: Britannia), there are fundamental questions as to where the unit was stationed between the reigns of Claudius and Hadrian. Several options are possible: it could have transferred to Britannia in the Julio-Claudian period (so, Holder); it could have remained along the Rhine until the reign of Vespasian, arriving in Britain under Cerialis, Frontinus, or Agricola; or it could have served elsewhere and transferred to Britannia sometime in the reign of Trajan (as Spaul argues). I tentatively place this unit in the ‘possibly in Britain before 71’ category despite a distinct lack of early evidence in Britain only because there are so few constitutions known in the period for the province.⁷⁵

Ala Classiana is difficult to tie down with precision as to when it arrived in Britain. With a lack of evidence prior to a constitution of 105 (RIB 2401.2), opinions have varied from the Claudian invasion down to the reign of Domitian. Cichorius had dated a veteran's inscription at Cologne to the mid first century, but the Epigraphische Datenbank Heidelberg now dates it to the second half of the second century (CIL 13.8306). Until new evidence sheds light on the regiment's first-century service record, I propose an open-ended arrival date from 43 to c. 80: dates when most auxiliary units were transferred to Britannia prior to 105.⁷⁶

Ala I Hispanorum Asturum is unattested beyond Britannia in the first century (CIL 2.1086: Domitianic; CIL 16.43: 98). Dates of its creation vary from the Julio-Claudian to Flavian periods, with most proposals stating it was raised for service in Britannia. Following Jarrett's proposal for CIL 2.1086, this unit would have been in Britain at least by the mid 80s,⁷⁷ leaving arrival dates from the Claudian invasion to the governorship of Agricola as possible.⁷⁸

Until the discovery of RMD 6.505 (=AE 2003, 1033a-be = AE 2004, 858: 98), it was presumed that Ala I Hispanorum Campagonum had spent the Flavian era in Pannonia before serving in Moesia Superior and Dacia or that it was created specifically for service in the Dacian Wars.⁷⁹ While the unit could have been levied as late as 73, it may have served in the lower Rhineland early in the reign of Tiberius, under the sobriquet ala Hispanorum tironum (AE 1992, 186), before transferring to Britain during the Claudian invasion, where it served until Trajan's Dacian Wars. Alternatively, the regiment could have been levied for Claudius’ invasion. In any case, the unit had left Britannia for Moesia Superior by 105 for Trajan's Dacian Wars where it is attested on a new constitution.⁸⁰ Campagonum then served in Moesia Superior until 112 before transferring to Pannonia Inferior by 114 (AE 2008, 1738: 111/112; RMD 3.153: 114).⁸¹

Ala I Pannoniorum Sabiniana is now attested on a constitution for Britannia in 98, 24 years earlier than previous evidence suggested (AE 2014, 1627). It is generally assumed the unit was raised in the first few decades of the first century in Pannonia and formed part of the Claudian invasion force (serving in either Pannonia or Hispania before that), since it is unattested elsewhere in the first century. Sabiniana is likely named after Nymphidius Sabinus, who is attested in Pannonia during the Julio-Claudian era (CIL 3.4269).⁸²

Ala I Pannoniorum Tampiana is generally assumed to be in Britannia by the Flavian era, perhaps as part of the Claudian invasion force, since it is unattested anywhere before the Flavian period. Like ala I Pannoniorum Sabiniana, this unit was likely created in the reign of Augustus or Tiberius and named after an early commander, a practice which appears to have ended in the mid 20s c.e. Around 85, a vexillation was sent to Pannonia from Britannia where it likely served in the Dacian and Suebic Wars, being stationed around Carnuntum (CIL 3.4466). It returned to Britannia by 98 and left the province shortly after 122 for Noricum (RMD 6.505 = |AE 2003, 1033a-be = AE 2004, 858: 98; CIL 16.69, RMD 5.360: both 122).⁸³

Cohors II Asturum equitata is first attested in Britannia at Llanio (RIB 407, 408). These two building inscriptions could relate to the foundation of the fort (73/4–77), where the unit may have been stationed as late as the 120s. Now that it is recognised there are two cohortes II Asturum – the other served in Germania during this period (AE 1951, 88) – scholars generally agree that during Agricola's governorship, likely after Mons Graupius, C. Iulius Karus, the regiment's prefect, received his rewards. II Asturum equitata is then attested on a constitution of 105 (RIB 2401.2). Since this unit did not arrive from Germania after 89, as previously believed, there is a great deal of uncertainty where our cohors II Asturum was stationed previously or when it transferred to Britannia. Until we can trace its early movements, the unit could have arrived anytime between 43 and c. 77.⁸⁴

Cohors IV Delmatarum served in the Rhineland during the Julio-Claudian era before transferring to Britannia, first appearing there on a constitution of 103 (CIL 16.48). The Epigraphische Datenbank Heidelberg dates three Rhineland inscriptions to 31–50 (CIL 13.7507, 7508, 11962),⁸⁵ which leads me to propose that the regiment was transferred either after the Boudica Revolt in 61 or in the 70s. But we cannot rule out Holder's proposal that it formed part of the Claudian invasion force. In the Trajanic era the unit is attested at Castell Collen in Powys, Wales.⁸⁶

Cohors I fida Vardulorum c.R. first appears in Britannia on a constitution of 98 (CIL 16.43). The date of its creation as well as when the cohort transferred to the province are uncertain. On its creation, Holder maintains that it was levied by the reign of Claudius and arrived after the Batavian Revolt. Solana Sáinz, meanwhile, assumes the unit was raised in the Flavian era to serve in Britannia. All we can tell is that fida and c.R. were both awarded prior to 98 and that the unit was created by 73 at the latest.⁸⁷

The Cohors II Gallorum veterana in Britannia should probably now be seen as separate from the one attested in Mauretania Caesariensis. Previously, this unit was first attested in Britannia only in 122 (CIL 16.69, RMD, 5.360), which left open the possibility that it had served in Mauretania before transferring after 107 (CIL 16.56). But the recently published diploma for Britannia from 98 makes this proposition less likely (AE 2014, 1627). This also definitively separates the unit serving in Britannia from that attested in Moesia. The cohors II Gallorum in Britannia could have arrived as early as 43 and possibly as late as the early 80s; from where remains uncertain.⁸⁸

The presence of a Cohors IIII Gallorum might suggest that there was a series of Gallic cohorts raised to serve in Britannia. Paul Holder advocates that the likeliest moment for the levy would be on the eve of the Claudian invasion. In the mid 70s a fort was established at Castleford in Brigantian territory and there is now evidence that cohors IIII Gallorum was stationed there in the Flavian era (AE 2010, 784 = RIB 2.2472). Later, the unit was stationed at Templeborough in the Trajanic period (RIB 619, 620) and appeared on a constitution of 98 (AE 2014, 1627).⁸⁹

IN BRITAIN BEFORE 71

As noted above, Cohors VI Nerviorum now appears on a Bloomberg Tablet dating to the 60s, disproving Holder's hypothesis that regular Nervian cohorts were founded in 71. Tomlin has suggested a deposit date of 65/70–80, but this is just a residual context. The commander of the unit on the tablet was Classicus (Tab. Lond. Bloomberg 33 = AE 2016, 932). Since this is a rare name, the editors propose that the Treveran rebel of 70, Julius Classicus, probably served as this unit's prefect in the early 60s. Classicus would then have served as a legionary tribune later in the 60s before his appointment as praefectus alae closer to 70. As a result, this cohort may be among the eight auxilia regiments transferred in 61 after the Boudican Revolt (Tac., Ann. 14.38). This evidence not only throws into doubt that all the Nervian cohorts came to Britain at the same time, but that they were created in 71. Cohors VI Nerviorum was still in Britain in 98 (AE 2014, 1627).⁹⁰

Roger Tomlin proposes that Cohors I Vangionum arrived in 61 as one of the eight units sent to Britannia after Boudica's Revolt, based on a recently discovered tablet dating to 67 found in the Bloomberg excavation (Tab. Lond. Bloomberg 48 = AE 2016, 944; Tac., Ann. 14.38). This new evidence may suggest Conrad Cichorius was correct that the cohort was already in existence in 50 fighting in the Rhineland rather than being an irregular unit (Tac., Ann. 12.27.2).⁹¹

NO EVIDENCE IN BRITAIN

The presence of other units in the same series always leaves the possibility that any number of these units served briefly in Britain before going elsewhere. There is no evidence of Cohortes IV–VII Batavorum after 70 and perhaps Alföldy was correct in suggesting that survivors of the civil war and Batavian Revolt were folded into the attested units.⁹² Cohors VIII Batavorum, however, has been found on Raetian diplomas from the Late Trajanic or Hadrianic eras.⁹³ Could it have served in Britannia in the 70s and left after Mons Graupius like several other units in the British garrison?

Cohors I Batavorum equitata (milliaria) could have served in Britannia, but it is both unlikely and unnecessary. Much like the ala I Batavorum pf. it may have remained in the Rhineland after the Batavian Revolt (see above, Batavian Units Post Revolt). If Petillius Cerialis transferred either, or both, of these units to Britannia, my guess – and that is as far as I can venture – is that Domitian ordered the unit's transfer to the Rhineland in time to serve in his Chattan War. Holder proposes that cohors I Milliaria earned pia fidelis in 89 while serving in Lower Germany, before transferring to Pannonia around 92, in time for Domitian's Danubian campaigns (CIL 16.42: 98; AE 2004, 1267: late first-century Moesian tile stamp). In Pannonia, the unit was stationed at Solva, with a break during the Dacian Wars, before transferring to Dacia in 118 (AE 2003, 1373: 102/103–118).⁹⁴

Cohors V Lingonum first appears on a constitution for Dacia in 110 and the unit was stationed from the Trajanic period onwards at Porolissum (CIL 16.163; AE 2011, 1068). While the regiment could have been levied as late as 85, many scholars propose that the unit was created at the same time as cohortes I–IV Lingonum and that it had served initially in Britannia before transferring to the Danubian frontier under Domitian or Trajan.⁹⁵

Jarrett proposed that Cohors V Nerviorum served in Britain, though there no is evidence for this unit anywhere.⁹⁶ It may not have survived into the Flavian era. The same assessment goes for Cohors III Tungrorum, which could plausibly have been the Tungrian cohort that had defected to Civilis (Tac., Hist. 4.16). There is slight evidence for a vexillation of cohors III Tungrorum in Raetia between 122 to 147, but the unit number in both cases is uncertain (RMD 25; CIL 16.94).⁹⁷

Like cohorts I and II, Cohors IV Tungrorum probably predates the post-Neronian civil wars. Two Tungrian cohorts were among Fabius Valens’ lower Rhineland forces (Tac., Hist. 2.14–15). While contemporaneous to the other Tungrian units, no one has contended that cohors IV ever served in Britain. The first firmly datable evidence for this unit is a constitution for Noricum dated to 31 August 95 (AE 2009, 993), which further suggests the unit existed since at least 70. Where it was stationed before 95 is uncertain. It is, of course, plausible that it had briefly served in Britain and departed to the continent with other forces, either for the Chattan or Dacian Wars.⁹⁸

CONCLUSION

Despite the latent uncertainty in reconstructing these units’ histories, the patterns revealed in this latest appraisal of the arrival of auxiliary forces to Britannia in the Flavian era are suggestive. There is enough evidence to indicate Holder's assertion that all these units arrived in 71 is highly unlikely. Not only are some of his proposed units certainly on the island prior to 71 (cohors VI Nerviorum and cohors I Vangionum), but the earliest constitutions in Britannia, namely those of 98, 103 and 105 c.e., open alternative reconstructions. If some, or many, of the soldiers receiving privileges in the earliest British constitutions had served their time in a single unit, there may be some hints as to when several of the units transferred to Britannia under the Flavians were created. As analysed on a case-by-case basis above, these constitutions could reveal units created for service in 73, 78 and 80, which coincides with either the planning phases or early phases of campaigns in Wales and northern England/Scotland.⁹⁹ To this list we may add the pre-existing auxilia units that accompanied Cerialis and legio II adiutrix in 71 to augment the island's depleted garrison and to help settle affairs among the Brigantes. Despite the broader and more conservative arrival dates for units proposed here, what becomes rather clear is that units were created and transferred to Britannia from the Rhineland and Gallia Belgica throughout the 70s and early 80s as Rome gradually expanded in Wales, northern England and Scotland, which required both shifting and augmenting the province's garrison. It is my hope that future discoveries will both refine our knowledge of Britannia's earliest garrisons and continue to enhance our understanding of Roman imperial plans for expansion on the island.