History Files

Please help the History Files

Contributed: 175

Target: 400

Totals slider

The History Files still needs your help. As a non-profit site, it is only able to support such a vast and ever-growing collection of information with your help, and this year your help is needed more than ever. Please make a donation so that we can continue to provide highly detailed historical research on a fully secure site. Your help really is appreciated.

Celtic Kingdoms of the British Isles

Celts of Britain


Caer Mincip / Verulamium (Romano-Britons)

FeatureWith the expulsion of Roman officials in AD 409 (see feature link), Britain again became independent of Rome and was not re-occupied. The fragmentation which had begun to emerge towards the end of the fourth century now appears to have accelerated, with minor princes, newly declared kings, and Roman-style magistrates all vying for power and influence while also facing the threat of extinction at the hands of the various barbarian tribes which were encroaching from all sides.

The post-Roman Trinovantes appear to have retained their identity to some extent, although their former territory had become fractured. Their tribal name does not seem to have survived, but in the few written records available this seems to have been typical of the south of Britain. Most post-Roman states appear to revolve around former Roman cities, and often bear their names except in the more lightly Romanised far west.

A possible successor kingdom to the western section of Trinovantes tribal territory seems to have formed around the important sub-Roman town of Verulamium. Sitting a little way to the north of Londinium, later writers knew it as Caer Mincip or Mincipit (modern St Albans is located alongside the ruins of the Roman city).

The city appears to have formed the hub of a British enclave which survived against the odds until around the start of the seventh century AD, possibly allied with nearby Cynwidion (on its northern flank). Whether it also controlled Londinium is unknown, but that city appears to have been largely abandoned from around AD 457, following the final defeat of British forces in Ceint.

The name Caer Mincip was derived from the Brythonic word for fort or citadel, 'caer' (Latin 'Castrum), and 'mincip' from municipium, which was derived from the Latin verb 'munio', meaning 'to fortify, defend, protect'. Modern English has derivatives such as municipal, municipality, and so on. So while later Britons remembered Verulamium in the abbreviated form of Caer Mincip in their writings, the sub-Roman Britons who actually inhabited it under increasing threat of conquest by the invaders probably called it Caer Minicipium, the 'defended fort'.

It should also be noted that the Brythonic language has gone through five stages to reach modern Welsh: 'Primitive' (in the 500s-700s), Old Welsh (in the 800s-1000s), Middle Welsh (in the 1100s-1400s), 'Early Modern' (in the 1400s-1700s), and 'Late Modern' thereafter. Until the Middle Welsh period, the word 'caer' was actually 'cair', from the Brythonic 'cajr', meaning 'fort, fortified place'.

Roman Canterbury

(Information by Peter Kessler, with additional information by Edward Dawson and Trish Wilson, from Roman Britain: A New History, Guy de la Bédoyère, from The Cambridge Historical Encyclopaedia of Great Britain and Ireland, Christopher Haigh (Ed), from The Oxford History of England: Roman Britain, Peter Salway, from the Historia Brittonum (The History of the Britons), Nennius (J A Giles, Ed & Trans, 1841, published as part of Six Old English Chronicles (Henry G Bohn, London, 1848)), from The Anglo-Saxon Chronicles, Anne Savage (translator and collator, Guild Publishing, 1983), from A History of the English Church and People, The Venerable Bede (Leo Sherley-Price translation - revised by R E Latham), from Vitus Germanus (The Life of Germanus), Constantius, from Alban and the Anglo-Saxon Church, Martin Biddle (Cathedral and City: St Albans Ancient and Modern, Robert Runcie (Ed), Martyn Associates, 1977), and from External Links: Britannia (dead link), and British History Online.)

209 / 251 / 304

Although the date of his death is disputed between three alternatives, Alban, or Albinus is martyred at Verulamium for his conversion to Christianity. He is the first-known Christian martyr in Britain which already has a poorly-recorded British Church administration. Even by the fifth century a cult exists in his name in what has probably become Caer Mincip, and the later St Albans Abbey is founded near the site.

Sequential Maps of Roman Britain AD 43-425
Emperor Severus visited the British provinces to lead a campaign in person against the Caledonii and Maeatae in 209-211, pursuing a scorched earth policy to try to bring the ephemeral tribesmen either to a pitched battle or to surrender, neither of which actually occurred (click or tap on map to view full sized)


The drains around the forum in Verulamium (Caer Mincip, the 'defended fort') have been well-maintained even during the years of decline in the later fourth century, but in the fifth century they become clogged. Either the forum has fallen out of use or the manpower or will for such maintenance work has died out.

Around the same time (at the end of the 300s) the mid-second century theatre in the city, which had been substantially enlarged around AD 300, is now in ruins, made redundant by the collapse of paganism in Christian Britain and the abandonment of the temple precinct with which it had been associated. Instead it is a rubbish dump.


With Constantine III now in serious difficulties in Gaul, further Saxon raids convince the Britons and Armoricans to rebel and expel Roman officials, thereby breaking ties with Rome which are never renewed. Roman presence in Britain has been dwindling anyway for at least the previous three decades, so the split probably produces little change, except that British officials now occupy former imperial posts.

FeatureRecords from this point become extremely sparse, and British control on a national level appears to break down for a time, either immediate or very shortly after this event (see feature link).

Verulamium (St Albans)
With the south gate of Verulamium (Caer Mincip, just outside modern St Albans) probably remaining in use until about AD 600, the town was part of a working Romano-British settlement which was set up to defend itself from increasing Saxon encroachment, although it is unlikely that the Roman baths at nearby Welwyn would have lasted quite so long (click or tap on image to view full sized)


St Germanus, bishop of Auxerre, and Lupus, bishop of Troyes, visit Britain to fight the Pelagian 'heresy' which is running rampant through the British Church. They meet with a still extant Romano-British aristocracy (the principle proponents of the heresy), probably at Caer Mincip.

Members of the Pelagian party turn out in their very best attire, according to the writer Constantius, 'conspicuous for riches, brilliant in dress, and surrounded by a fawning multitude'. They are every inch the proud Gallo-Roman nobility which had been so evident in fourth century.

They make it very clear to their continental European visitors that they are not a ruined class which is living in bondage to savage barbarian masters (as some of their contemporaries in Gaul are already doing), nor even a few fortunate survivors, but a substantial body of men of influence who carry weight both with their personal following and with the community at large.

St Germanus later promotes the cult of St Alban after visiting Caer Mincip's church which is dedicated to the martyr (close to or now under the abbey church in today's city of St Alban - and medieval abbots divert Watling Street away from the Roman ruins they see in Caer Mincip and closer to the church, thereby encouraging town-building around them).

St Germanus of Auxerre
The Alleluia Victory saw St Germanus lead the Britons to a bloodless victory over marauding Saxons, perhaps demonstrating that the country was finally managing its own defence


Archaeological investigation between 2000-2012 on a site which lies immediately adjacent to Watling Street at Whitehall Farm in Nether Heyford (to the north of Verulamium, probably within Cynwidion's territory) reveals a small Anglo-Saxon cemetery. Its earliest burial is dated to around this time (although the bulk of them date to the seventh century).

Curiously the cemetery is located next to a Roman villa and farm. The villa is a sophisticated one, with its own bath house complex, and is the centre of an agricultural estate which extends over about four hectares. If this is still active at this time then the first Saxons to arrive may even be employed as farm workers.

c.480 - 500

The region comes under pressure from Saxons to the south who are infiltrating from the Thames Valley and settling as the Ciltern Saetan (Chiltern settlers). Separate Saxon groups from the advancing Middil Engle quickly push in Cynwidion's northern borders, finding a way through the Vale of Aylesbury and compressing this state into the more defendable Chilterns and Buckinghamshire, still most likely with a direct connection to Caer Mincip.

Map of Britain AD 450-600
This map of Britain concentrates on British territories and kingdoms which were established during the fourth and fifth centuries AD, as the Saxons and Angles began their settlement of the east coast (click or tap on map to view full sized)

c.575 - 600

FeatureCaer Mincip shows plenty of evidence for the survival of a British enclave. The town is located between the territory of the Middel Seaxe (immediately north and west of Londinium - see feature link) and the Icknield Way. Its survival may be the last gasp of Trinovantes independence, although the city had originally been founded as the capital of the Catuvellauni.

A late Roman building has been converted into a barn or granary by the application of huge buttressed foundations. Corn dryers have been inserted inside the building so that such agricultural work can take place within the safety of the town walls. A wooden water pipe is later constructed across the site and is maintained, quite possibly until the collapse of the enclave at the end of the sixth century.

This date of Caer Mincip's collapse is very close to that of Cynwidion's collapse, and that territory lies to the immediate north of Caer Mincip. It seems likely that, in its final days, Caer Mincip is an outpost or appendage of Cynwidion, and perhaps a final survivor of a postulated Caer Lundein territory before that.

Chiltern Hills
The Chiltern Hills contain territory which was probably easy to defend for the warriors of the post-Roman kingdom of Cynwidion, at least initially and in part, but Angles and Saxons who formed the Ciltern Saetan cut them off to the west and eventually forced their collapse

That it has survived at all is probably due to the weakened state of many southern Saxon kingdoms after their Mons Badonicus defeat of around 496. Lundein (Londinium, modern London) is taken by the East Seaxe, while Caer Mincip is generally abandoned in favour of a new English city alongside it, known as St Albans.

Images and text copyright © all contributors mentioned on this page. An original king list page for the History Files.