Chester in the seventh century: the fortress defences

Roman Chester was founded in around 74 AD as the legionary fortress of Deva, later called Deva Victrix from the name of its garrison, the Twentieth Legion Valeria Victrix. As a legionary fortress, it would obviously have been provided with a defensive wall. What were the defences like, and were they still standing in the seventh century?

Evidence

The Roman defences

The initial Roman fort built in 74 AD or thereabouts had a turf and timber rampart. This may have been intended as a temporary structure from the start, and was soon replaced by a stone curtain wall. The date of completion of the stone defences is unknown, but usually placed somewhere around the turn of the first and second centuries (Mason 2001). On the south and west sides of the fortress, the Roman defences were demolished in the medieval period and replaced by defences extending to the river, so only the foundations and first few courses of the Roman walls survive to be recognised in archaeological excavations. On the east and north sides, some stretches of the Roman wall still stand to a considerable height with the later medieval walls on top.

Chester’s curtain wall was unusual, as it was entirely built using the monumental construction technique called opus quadratum, usually reserved for prestige structures such as gates. Large stone blocks up to 6 feet (1.8 m) long and 3.5 feet (1 m) wide were laid in courses 10–15 inches (25–36 cm) high, without using mortar. The wall was 4.5 feet (1.35 m) thick, reducing to 3.5 feet (1 m) at the top, and had an elaborate moulded cornice below the parapet (Mason 2001). This flashy form of construction is consistent with Chester having a higher status than other legionary fortresses in Britain (more on this in a later post).

The wall was built immediately in front of the original rampart, and the space between the wall and the front face of the old rampart was filled with rubble mixed with clay (mixed with mortar in the section between the south and east gates. This may indicate different work parties using different techniques in different sectors, or different phases of construction (Mason 2001).

How long did the defences stand?

A section of the north wall was taken down and rebuilt in the late nineteenth century, when it was found to contain re-used Roman tombstones and pieces of architectural sculpture. This could hardly belong to the original stone wall, as the fortress had only been in existence some 20 years at the time, surely not long enough to have generated large quantities of tombstones to be requisitioned for building work. Some of the tombstones commemorated serving legionaries who were married and thus probably third century. One commemorated Gabinius Felix, a soldier of legion II Augusta, and gave his legion the title Antoniniana, which was current in 213–222. The tombstone was very weathered, suggesting it was re-used in the wall no earlier than the late third century.

Further investigations have suggested two distinct phases of rebuilding of Chester’s curtain wall, both using large quantities of recycled Roman masonry and tombstones. In one phase the replacement wall was about 10 feet thick, roughly twice the thickness of the original wall, and this has been identified on the north wall immediately west of the north-east corner, and on the west wall north of the west gate.

In the other phase, the replacement wall was about 5 feet thick, roughly the same as the original wall. This rebuild has been identified on the north, east and west walls of the fortress. A section of this rebuild south of the east gate (at the Old Public Library on St John’s Street) allowed some of the sequence to be reconstructed. This showed that the ditch in front of the original Roman fortress wall had silted up completely to ground level, and on top of the soft fill lay a mass of heavy rubble including some damaged facing stones from the fortress wall. This is consistent with the wall having collapsed forwards and outwards (the wall leans outwards in the sections that are still standing further north along the east wall). This collapse might have been spontaneous or might have been deliberate demolition to make the site safe before beginning the rebuild. The rubble had been covered with a layer of sandstone brash up to 1 foot thick, and the wall rebuilt from the fourth course upwards, to the original width of about 5 feet, backed by clay instead of the original mortar, and containing at least one moulded block re-used from somewhere else. This rebuilt wall had itself collapsed, forwards and outwards again, onto the layer of sandstone brash. The rubble from this second collapse had eventually combined with the collapsed and weathered rampart behind to form a low mound. David Mason says there was evidence for a subsequent refortification, before the existing medieval wall and massive ditch was built in its current alignment probably in the late twelfth century. (Unfortunately, he doesn’t specify what the evidence for the post-Roman pre-medieval refortification consisted of).

Neither of the rebuildings can be securely dated. Mason concludes that the narrower rebuild probably belongs to the first quarter, of the fourth century and may be associated with an overhaul of Britain’s infrastructure and defences after Constantine the Great came to power. The thicker rebuild is identified as later on the basis of constructional technique. A single coin of Constantius II Caesar (324–337) was found in the thicker rebuild east of the north gate. Mason says that it means little by itself but does not elaborate; my guess is that a single coin could have been picked up accidentally along with the recycled building material and could have come from anywhere. At one point (p.211) he says the thicker rebuild could belong to the overhaul of army installations conducted by the elder Theodosius in about 370 AD, after the Barbarian Conspiracy, and at another (p. 204) he says it could be post-Roman and perhaps as late as the tenth century.

Documentary evidence

Annales Cambriae

601 The synod of Urbs Legionis [Chester].

--Annales Cambriae

This is probably the same synod mentioned by Bede for 603 or 604 AD. The use of Chester as a site for a major synod indicates that the city was still important, but does not necessarily say anything about the state of the defences.

The Anglo-Saxon Chronicle mentions Chester twice at the end of the ninth century:

AD 894.
....they [the Danish army] marched on the stretch by day and night,
till they arrived at a western city in Wirheal that is called
Chester. There the army could not overtake them ere they arrived
within the work: they beset the work though, without, some two
days, took all the cattle that was thereabout, slew the men whom
they could overtake without the work, and all the corn they
either burned or consumed with their horses every evening.

AD 907
.... Chester was rebuilt.

--Anglo-Saxon Chronicle

The 894 entry suggests to me that the English army tried to overtake the Danes before they arrived “within the work” at Chester, and therefore that Chester still had defences that were sufficiently serviceable to be of military use. The Chronicle often refers to “a work” in a context that implies it meant defensive earthworks. It also suggests to me that Chester and/or its immediate surroundings had sufficient of a population to have cattle and corn. The 907 entry suggests to me that Chester’s defences were incomplete enough to require rebuilding.

Interpretation

Clearly, the parts of Chester’s Roman walls that are still standing now (north wall and the east wall north of the east gate) would have been standing in the seventh century. It is impossible to be sure how much of the west and south walls were intact before they were demolished to extend the defences.

The second collapse of the rebuilt east wall south of the east gate was apparently left as rubble long enough to combine with the remains of the collapsed rampart behind, implying a long period without repair. If David Mason is correct that there was a subsequent refortification which predated the medieval wall, this is consistent with a long period of disrepair during the early medieval period, followed by a refortification either when the Danes briefly took the city in 894 or when “Chester was rebuilt” in 907. Since the wall was rebuilt to its original width and on its original foundation, it’s a reasonable first approximation that the rebuild may have stood about as long as the original. If the original stone wall was finished in the early second century (say 110 AD), and was demolished immediately before the rebuild was carried out in the early fourth century (say 310 AD), the original wall stood for about 200 years. If the rebuilt wall managed the same, it would have collapsed in the early sixth century (say 510 AD). It’s unlikely to have collapsed while the Roman Army was still in residence (i.e. up to c. 400 AD) or one would expect it to have been repaired again, and is perhaps unlikely to have stood much beyond, say, the early seventh century given the implied long period of disrepair. So we could tentatively assign a date of c. 500 AD, plus or minus a century or so either way, for the collapse of the rebuilt wall south of the east gate.

It is possible that the thicker rebuild of the curtain wall using recycled stone was part of the 907 rebuilding. However, the “refortification” of the east wall south of the east gate mentioned by David Mason presumably did not conform to the same pattern as the thicker rebuild, or one would expect him to have said so. So either there was a reason why the same fortification used different techniques, or they occurred at different times. I favour the latter as a simpler explanation.

On balance, I would suggest the following approximate sequence:

• AD 100 approx – stone curtain wall built.


• AD 260 – 310 approx - Chester largely abandoned while the Twentieth Legion is fighting elsewhere in the Empire. The ditch silts up and parts of the curtain wall collapse due to lack of maintenance.


• AD 310 approx – Damaged parts of Chester’s curtain wall repaired to original width.


• AD 370 or later – Other damaged parts of Chester’s curtain wall, which had presumably not needed repair in 310, rebuilt to double width.


• AD 500 approx (plus/minus a century) – Part of the wall rebuilt in c. 310 collapses south of the east gate and the breach is ignored, the rubble being left to combine with the collapsed rampart. Either the breach was still defensible with a sufficiently large and determined force, or Chester was not an important defensive structure at the time, or any repair/refortification has not left any evidence).


• AD 907 – Chester refortified by Aethelflaed Lady of the Mercians to create a defensive burh.

References
Full-text sources available online are linked in the text.
Mason DJP. Roman Chester: city of the eagles. Tempus, 2001, ISBN 978- 0-7524-1922-0.