Around the year 600 the political map of northern Britain looked very different from anything we would recognise. Most of what is now southern Scotland and northern England spoke a Brythonic language, the ancestor of Welsh. Their territory was the Hen Ogledd, the Old North, a patchwork of Brythonic kingdoms whose memory survives largely in Welsh tradition because their direct heirs were absorbed into England. The Gododdin were one of these peoples, descendants of the earlier Votadini whom the Romans had known and traded with. Their stronghold was Din Eidyn. To their south, the Angles - Germanic settlers who had crossed the North Sea generations earlier - had built two aggressive kingdoms: Bernicia, centred on Bamburgh, and Deira, centred on York. The two would eventually merge into Northumbria, a power that would dominate the north for centuries.

Catraeth is almost certainly Catterick in North Yorkshire, the old Roman station of Cataractonium on the Great North Road. By 600 it was in Anglo-Saxon hands, a forward post of Deiran power. The poem describes a Gododdin force of about 300 mounted warriors, drawn from across the Brythonic world - some came from Gwynedd in North Wales, some from Pictland north of the Forth. Mynyddog feasted them at Din Eidyn for a full year before the campaign, building loyalty and bonds. Then they rode south. The historian Kenneth Jackson, who edited the most authoritative modern edition of Y Gododdin in 1969, doubted that 300 men alone could have undertaken the task and suggested that a much larger force of foot soldiers must have accompanied them, simply too humble for the poet to name. The 300 in the verses are the elite cavalry, the warband worth remembering.

The battle itself was a catastrophe for the Britons. They were opposed by a larger Angle army from both Deira and Bernicia, and they were nearly all killed. The poem is structured around the deaths, stanza by stanza naming the warriors and praising their courage and their bright weapons. Some scholars read it as an attempt by the Britons to push back Anglo-Saxon expansion. If so, it failed catastrophically. Within a generation or two, the Gododdin kingdom was absorbed by the Angles and its territory folded into the growing kingdom of Northumbria. The Brythonic tongue of the Old North was gradually replaced by Old English. The poem outlived the people it described. Y Gododdin survives in a thirteenth-century Welsh manuscript called the Book of Aneirin, copied and recopied through monasteries in Wales after the originating culture had vanished. It is the only direct testimony we have of the warriors of the Hen Ogledd.

Y Gododdin matters because it is one of the earliest pieces of vernacular European poetry we possess - perhaps the oldest surviving Welsh literature, certainly the oldest substantial poem from anywhere in what is now Scotland. Modern fiction keeps returning to it. John James used Y Gododdin as the basis for his 1969 novel Men Went to Cattraeth. Rosemary Sutcliff retold the story from a shield-bearer's viewpoint in The Shining Company in 1990. Richard Denning approached it from the Anglo-Saxon side in his 2010 novel The Amber Treasure. Nicola Griffith's 2014 historical novel Hild builds the epic into the imaginative life of her seventh-century protagonist. The actual battlefield, if Catterick is correct, is mostly buried under modern development - the Catterick Garrison army base, the A1 motorway, and a small Yorkshire town. Stand near the Roman fort site today and there is nothing to see. But under the ground are the bones of warriors whose names, in many cases, we still know.