Birdoswald Roman Fort: dating the post-Roman use of the site

In an earlier post, I described the post-Roman timber halls constructed on the site of the north granary in the Roman fort of Birdoswald on Hadrian’s Wall. We know the halls are post-Roman because late Roman coins of Valentinian, dated to the 380s, were found beneath the relaid floor. How long did the site remain in use after the end of Roman occupation?

Dating the post-Roman halls

Unfortunately, there are no surviving timbers from the post-Roman timber buildings that could be dated by dendrochronology or radiocarbon, and there are no datable objects from the site after the coin of Theodosius found under the collapsed roof of the south granary (Wilmott 2001 p. 123). So dating the post-Roman halls is a matter of interpretation.

There are two distinct timber building phases to accommodate, the first one built more or less directly on top of the north granary and the second one built partly on the north granary and partly on the adjacent street. Both must post-date the coins of Valentinian found under the flagstone floor, so both must post-date the 380s. If the timber buildings replaced the function of the south granary, whose roof collapsed some time after the worn coin of Theodosius (388-395) was dropped on its floor, they also post-date this collapse.

Tony Wilmott suggests that the south granary roof collapsed in the early fifth century, say around 420, as the coin of Theodosius was very worn and thus had been around for some considerable time. If the first timber building on the north granary site was constructed around this time, and if each phase had a life of 50 years, this would suggest the second timber building was constructed around 470 and lasted until around 520 (Wilmott 2001 p. 123-4).

Needless to say, these are very approximate estimates. Timber buildings can and do last a lot longer than 50 years if the structural timbers are supported on stone foundations (as both the Birdoswald buildings were), as witness the medieval and early modern timber-framed buildings that still survive in Britain today. Conversely, a timber building can have a life considerably shorter than 50 years if bad weather, accidental damage, poor construction or bad luck intervene, or if the owner simply decides he feels like replacing it. And although a collapsed building is unlikely still to be occupied, the reverse is not necessarily true; a building could be abandoned for social, political or personal reasons long before it actually falls down. The issue date of a coin can be identified accurately, and this gives the earliest possible date for its loss or deposition, but the actual date of its loss or deposition could be later, perhaps much later, than its date of issue, depending on how long the coin was in circulation (or in storage).

Furthermore, it’s difficult to be sure whether a site was continuously occupied or whether it went in and out of use, if the periods of disuse were too short for archaeologically recognisable deposits to form, or if any such deposits were cleared at subsequent re-use rather than built over. Ken Dark reviews the same sequence of evidence from Birdoswald and proposes a break in occupation between the residential use of the south granary and the buildings constructed on the north granary. In this scenario, he suggests that the south granary was in use as a residential hall during the last decades of the Roman occupation (roughly 350 to 400), that the fort was then abandoned for a period after the end of Roman government, and that the fort was re-occupied some time during the later fifth or sixth century, at which time the site of the north granary was cleared and the timber buildings constructed (Dark 2002, p.198-199).

Another possibility that occurs to me is that there may have been a break between the first and second timber building phases. Since the second timber building was partly on top of the site of the first, the first must have collapsed or been demolished before the second one could be built. Demolition and building might have been quite quick, if all the required materials were assembled and pre-prepared on site beforehand, but that requires efficient logistics and even then the replacement of one building by the other could hardly have been the work of a day. Abandonment of the site, perhaps only briefly, allows for site clearance and the subsequent construction of the second timber building.

It is worth bearing in mind that abandoning the area of the granaries does not necessarily mean abandoning the entire fort site. Areas of occupation may have moved around according to the condition of existing structures and the availability of sites for rebuilding. A barrack-type building constructed in the late Roman period (later fourth century) had re-used an inscription from the commanding officer’s house (praetorium) and another inscription commemorating the rebuilding of the granary, indicating that these buildings had gone out of use while other areas of the site were still occupied and in use.

Only the area around the west gate at Birdoswald has been excavated to modern standards, and it is possible that other early medieval structures may have stood elsewhere in the fort. Early excavations would not have picked up the slight traces left by timber buildings, and parts of the fort interior have not been excavated at all. Medieval ridge-and-furrow plough marks cover the southern third of the fort interior, with the exception of an area in the south-west corner where there is also a long flat platform against the fort wall. This has been suggested as the site of a medieval building (Wilmott 2001, p.133, 135); if so, perhaps the area might also have been in use earlier. The foundations of a square tower, possibly dated to the fourteenth/fifteenth century, were discovered in excavations north of the west gate (Wilmott 2001 p. 137). The west gate was probably still standing when the tower was built, as the pottery found under the rubble of its collapsed arch indicates it collapsed in the later fifteenth century, and Wilmott suggests that the first-floor storey of the gate was re-roofed and used as a hall building to go with the tower (Wilmott 2001, p. 138). If the west gate was sufficiently intact to be re-roofed and occupied as a hall in the fourteenth century, perhaps the same also applied several centuries earlier.

Interpretation

It’s clear from the timber halls that occupation at Birdoswald continued beyond the end of Roman government in Britain, for an unknown period that was long enough to construct two successive large timber buildings on the same site. The size of the halls implies that whoever ordered their construction controlled substantial resources of materials and manpower. It’s a reasonable inference that this was a local or regional ruler.

Although the halls are built on a Roman site, and the first one directly re-used surviving Roman walls as part of its structure, they are built of timber not masonry. This implies that Roman building techniques had been lost, either due to lack of knowledge or lack of the infrastructure to obtain the appropriate materials, or deliberately rejected.

The duration of post-Roman occupation is unknown, but must surely extend until at least well into the fifth century, unless the timber buildings had absurdly short lives, and could easily extend well into the sixth century or beyond, particularly if there was a break in occupation. The long cist grave found nearby is consistent with a burial of early medieval date, and is consistent with its occupant having been a Christian. One could speculate that the long cist grave represents the burial of a Christian ruler who lived in the timber hall, but this really is clutching at straws.

The eighth-century pin found nearby may indicate that the site was in use at this date, especially if the timber halls on the north granary site were succeeded (with or without a break in occupation) by other structures elsewhere in the fort, but this is unsubstantiated.

The place name, combining an Old English personal name with a Brittonic topographical description (“pen or farmyard of Oswald”) is most likely to have been coined some time in the early medieval period in the centuries after the end of Roman rule (since no trace of the Roman name remains in the modern name), but before the eleventh century when Old English names largely went out of fashion following the Norman Conquest and perhaps more likely before the Norse/Viking influence of the ninth and tenth centuries. The absence of any trace of the Roman name of the fort, Banna, in the modern name is consistent with a period of abandonment at some time after the end of Roman rule, long enough for the name to be lost, followed by re-occupation some time in the early medieval period. However, it could also be consistent with deliberate replacement of the old name by someone who wanted to emphasise a change of ownership or political allegiance. Whether “Oswald” refers to the sort of individual who might have owned and feasted in the timber halls, or to a humbler farmer working the site as agricultural land, or anything in between, is anyone’s guess.

On the whole, I would say that occupation until well into the sixth century is supported by the timber halls. This could represent continuous occupation without a break from the Late Roman period, or could represent reoccupation of a temporarily abandoned site. Further occupation into later centuries – with or without a break - is not unreasonable, but the only evidence for it is the eighth-century pin and perhaps the place name, which is not exactly definitive.

If Birdoswald was the base of an important local ruler in the later sixth century, this brings it into the same sort of period as the battle of Arthuret, entered in the Annales Cambriae in 573. Arthuret is traditionally located near Longtown in Cumbria, which is less than 20 miles from Birdoswald. I mentioned Arthuret in my article about Peredur. More about the battle in a later post.


References
Dark K. Britain and the end of the Roman empire. Tempus, 2002. ISBN 0-7524-2532-3.
Wilmott T. Birdoswald Roman fort: 1800 years on Hadrian’s Wall. Tempus, 2001. ISBN 0-7524-1913-7.


Map links
Birdoswald – Streetmap
Birdoswald – Google Maps satellite image
Longtown


Note for readers of Paths of Exile
I based the (fictional) warlord’s hall at Navio Roman Fort (modern Brough, Derbyshire) in Paths of Exile on the second of the post-Roman timber halls excavated at Birdoswald. There is no evidence that Navio fort was occupied by a local warlord in 605/606 (nor is there any evidence that it wasn’t).

Birdoswald Roman Fort: post-Roman activity on the site

Location of Birdoswald

Birdoswald is a Roman fort on Hadrian’s Wall in north-west England. It’s the sixth fort from the western end of the Wall, sitting on the western edge of the Pennines where the hills start to roll off into the plain of North Cumbria and the Solway Firth. The fort site itself is strategically located on a steep-sided promontory formed by a deep meander of the River Irthing, with wide-ranging views in all directions. It occupies the western end of the communication route across the Pennines formed by the valleys of the Rivers Irthing and Tyne, and commands the crossing of the River Irthing at Willowford.

The location was compared to Troy by a romantically-minded eighteenth-century Earl of Carlisle and an estate agent trying to sell the property in 1901. Like most such comparisons a large grain of salt is required – I can’t see many people arriving at Troy, either Homer’s legendary city or Schliemann’s Hissarlik, and saying “Lo, behold the Birdoswald of Asia Minor!” Nevertheless, it’s an impressive, if rather rain- and windswept, site. Scroll around and zoom in and out of the map and satellite image links at the bottom of the page to get an idea.

Place name

The Roman name of the fort was Banna, attested by an altar found at the site in 1821 and dedicated to the woodland god Silvanus by the ‘Venatores Bannienses’, which translates as ‘the hunters of Banna’. Until recently it was thought to have been called Camboglanna*; however this is now thought to have been a mistake in the Notitia Dignitatum (Wilmott 2001 p. 97).

The modern name Birdoswald is first recorded as ‘Burthoswald’ or ‘Bordoswald’ in 1194-1220, when charters granted land there to the Priories at Lanercost and Wetheral (Wilmott 2001 p. 131). The name elements consist of the Old English man’s name Oswald and the Brittonic (Welsh) element ‘burth’ or ‘buarth’, meaning a pen or farmyard (Ordnance Survey glossary of place name elements), so the name means ‘pen or farmyard of Oswald’. The name elements are ordered in the Welsh format, with the personal name second (Old English names are typically ordered with the personal name first, in the format ‘Oswald’s farm’). This suggests to me that the name was coined and established by people who spoke Welsh or its Brittonic ancestor.

The most famous Oswald associated with the approximate locality is the seventh-century king of Northumbria, killed in battle in 642 and revered as a saint (Bede, Book III ch. 9), but as far as I know there’s absolutely nothing to connect him with Birdoswald except the obvious romantic appeal of such a notion. Incidentally, I don’t think the ‘buarth’ element of the name necessarily rules out a royal or aristocratic connection. Assuming that the ‘pen’ meaning of ‘buarth’ meant a livestock pen, a place where animals could be corralled, it could refer to the gathering of livestock for payment of tax or tribute as well as to agricultural use.

Post-Roman occupation at Birdoswald: the timber halls

The buildings visible in the north-west corner of the fort on the satellite image are those of the Georgian and Victorian farm, now a modern visitor centre. Occupation at Birdoswald is attested – though not continuously – from the Roman period to 1984, when the last farming tenants moved out. Much of the information we have comes from a series of excavations led by Tony Wilmott in 1987-1998 (for a fascinating, detailed and very readable account, I highly recommend his book on the subject, see references for details).

For the purposes of this post, I’ll focus on the post-Roman phases of construction and occupation at Birdoswald on the site of the former fort granaries, discovered and excavated in 1987.







Sketch plan of the location of the Roman granaries in Birdoswald fort (A) and of the second-phase post-Roman timber hall in relation to the north granary (B)
















Photos of the posts marking the site of the timber halls and the granary foundations on Gabriele's blog here.

The Roman fort at Birdoswald had two large stone granaries, built between the central headquarters building (principia) and the west wall, south of the west gate (see sketch plan A). The exercise basilica or indoor drill hall (which must have been a welcome facility in rainy north-west England) and a long rectangular building of uncertain function stood opposite the granaries, north of the west gate (for pictures of the reconstruction of the slightly smaller exercise basilica at Saalburg in Germany, see Gabriele’s post). The granaries were built some time in the second century (date uncertain) and repaired or rebuilt according to an inscription in 205-8. Around the same time, early to mid third century, the south portal of the west gate was walled up (Wilmott 2001 p. 93), leaving the north portal in use.

The stone roof of the north granary collapsed in around 350, dated by a coin of 350-353 found beneath the drifts of fallen roof tile, and the ruins were then used as a rubbish dump (Wilmott 2001 p. 118).

At about the same time, the south granary had a new stone floor laid (dated by the coins found beneath the floor, which cease in 348) (Wilmott 2001 p.119). This floor later became covered with deposits of silt interspersed with patches of stone, and two successive hearths were built at the western end. Around the hearths were found a fourth-century glass finger ring, a gold and glass earring, and a worn coin from the reign of Theodosius (388-395) (Wilmott 2001 p. 121). The hearths indicate residential use, the jewellery suggests the presence of women, and the presence of jewellery and a coin indicates high-status occupation. This is consistent with the south granary being used at this period as something akin to a chieftain’s hall. The jewellery, coins, hearths and stone floor were found beneath a layer of collapsed stone roof tiles, indicating that the roof fell in some time after the date of the coin (Wilmott 2001 p.121).

The north granary had been used as a rubbish dump after its roof collapsed in around 350, and the rubbish deposits included coins dated to the 380s and two penannular (ring) brooches of a type dated to the very end of or just after the Roman period in Britain (Wilmott 2001 p.121). A new flagstone floor was laid on top of these deposits, and shallow post-holes were made in the tops of the surviving walls by removing a few stones from the wall core. At the western end, the post-holes continued beyond the end of the original granary structure, encroaching on the Roman street. This suggests that the north granary was rebuilt as a timber building, re-using the remaining Roman walls as foundations (Wilmott 2001 p. 121). This timber building was the same width as the Roman granary and a little longer, and was therefore a large building, something like 25-30 m long. This is comparable with the size of the fifth/sixth century hall excavated at South Cadbury (though a different shape; the South Cadbury hall was 10 m x 20 m, while the Birdoswald granary was longer and narrower), so it was big enough to be the hall of an important ruler. It must have been built after the 380s on the evidence of the coins beneath the new flagstone floor. If it was the functional replacement of the “chieftain’s hall” in the south granary, then it was presumably built at or after the time of the roof collapse in the south granary.

At some later date, this timber hall constructed mainly on the foundations of the north granary was replaced by a second timber building with a different footprint. This second timber building was also hall-sized, 23 m by 6.8m, and was built partly over the site of the granary and partly over the adjacent street to its north (see sketch plan B). On the street, a line of stone post pads that would have supported timber posts were laid on the street surface, and on the granary shallow trenches were cut into the floor and stone post pads laid on the bottom of the trenches (Wilmott 2001 p.121). The north wall of this second timber building aligned with the centre pillar of the west gate; as the south portal of the gate had been walled up in the Roman period (see above), the hall was now lined up about as closely as it could get to the current entranceway, and would have been the first structure seen by anyone entering through the west gate (Wilmott 2001 p.121). (Constructing a hall directly opposite the gate would probably have been difficult because of the rectangular building and the exercise basilica on the north side of the street. Whether the exercise basilica was still intact or partly ruined by this date its massive walls and pillars would presumably have constrained any subsequent construction for some considerable time).

Both these big timber halls on the site of the north granary were associated with smaller timber buildings built against or close to the western fort wall, south of the west gate.

Other post-Roman evidence from Birdoswald

There is no definite archaeological evidence from Birdoswald between the post-Roman timber halls described above and one medieval pottery sherd from the twelfth/thirteenth century (Wilmott 2001 p. 129, 135). All there is from this intervening period is:

• a sixth-century Anglo-Saxon cruciform brooch of the type called ‘small-long’, of doubtful provenance but probably found at Birdoswald in the 1830s (Wilmott 2001 p. 123);


• a long cist grave found beside Hadrian’s Wall to the east of the fort site in 1956, ‘post-Roman’ but otherwise undated (Wilmott 2001 p. 172);
• 
  
• an eighth-century Anglo-Saxon disc-headed pin found outside the fort to the east (Wilmott 2001 p. 129).

The Anglo-Saxon brooch and pin could indicate contemporary trade contacts, conquest, loot, travel, occupation, marriage links or many other interpretations besides, or perhaps just a casual loss at some much later date. It’s impossible to read much into two isolated finds; the most that can be said is that they are not inconsistent with early medieval occupation or activity at Birdoswald, perhaps extending beyond the likely date of the post-Roman timber halls.

A long cist grave is essentially a stone box or coffin constructed within the grave, usually from stone slabs. As far as I know they are usually associated with early Christian sites in Britain, and Ken Dark considers them to be an indicator of a late/post-Roman Christian culture that spread in the fifth and sixth centuries to areas that had been outside or on the periphery of Roman Britain, such as Wales, Cornwall and the region north of Hadrian’s Wall (Dark 2002). Long cists are widespread in fifth- and sixth-century cemeteries in south-eastern Scotland (Dark 2002, p. 203), which is not so very far from the Birdoswald area. Furthermore, the centurion’s quarters at the end of one of the barrack buildings in the north-west corner of Birdoswald fort was remodelled some time in the late fourth century and acquired a rounded west end (Wilmott 2001, p. 119). This may be an apse, which in turn may indicate that the building was being used as a Christian church, which in turn may indicate that at least some of the occupants of the fort were Christians. A single long cist grave, undated, could mean almost anything. Again, about the most that can be said is that it would not be out of place for an early medieval Christian living at Birdoswald to be buried in a long cist grave.

How long did the post-Roman occupation of Birdoswald last? More on this in a later post.


* Camboglanna is now thought to refer to the next fort west, at the modern site of Castlesteads. Camboglanna is one of the candidates for King Arthur’s (legendary?) last battle at Camlann, favoured by proponents of a northern location for King Arthur.

References
Bede, Ecclesiastical history of the English people. Translated by Leo Sherley-Price. Penguin Classics, 1968, ISBN 0-14-044565-X.
Dark K. Britain and the end of the Roman empire. Tempus, 2002. ISBN 0-7524-2532-3.
Ordnance Survey glossary of place name elements, available online
Wilmott T. Birdoswald Roman fort: 1800 years on Hadrian’s Wall. Tempus, 2001. ISBN 0-7524-1913-7.

Map links
Birdoswald – Streetmap
Birdoswald – Google Maps satellite image