It was a bleak place to die. The moors rose steeply from the east bank of the Devil’s Water, their flanks and summits bare of cover. The river itself, which had provided the remnants of the retreating army with some protection at the start of the rout, now boxed them in. Coming to another stream, Denis Brook, the leader of the retreating men signalled those still left with him to turn and make a stand. The moors rose up to the south. There was no escape that way, not with their pursuers following so close behind. The only chance was to buy a little time, to bloody the hunters so that they had to stop and regroup, and then attempt to escape.


Cadwallon, King of Gwynedd, the most successful warlord in the British Isles, ranged his retainers beside him, anchoring the flank against the river. There were so few of them now that he could do nothing to protect the right wing of his shield wall. They waited. But they did not have to wait long.

The man leading the pursuers had been given a nickname, Lamnguin, when he was still a boy. Lamnguin meant 'white blade'. But it was not white any longer. The pursuer's name was Oswald and with him were warriors from the Gaelic kingdom of Dál Riata, a small contingent of monks from the Holy Isle of Iona, and Oswiu, his younger brother. Oswald had spent much of his life in exile in Dál Riata, while rival Anglo-Saxon strongmen and then King Cadwallon had wielded power in his native Northumbria. Now he had returned to claim the kingdom.

The final battle was brief but bloody. At its end, Cadwallon and his men lay dead, their weapons robbed, their bodies stripped of the garnet-inlaid gold buckles and arm rings so beloved of seventh-century warriors. Oswald’s triumph was complete.

Glory-hungry men

If Cadwallon’s death was brutal, it was hardly unusual. Early medieval history is littered with kings who seized power at the point of a sword and attracted glory-hungry young men to their warband, until a battle too far ended in their utter defeat. But Cadwallon was different, and so was the clash at which he made his last stand. Today, few people have heard of the battle of Heavenfield. Its precise location – just over 20 miles west of Newcastle in modern-day Northumberland – was lost to history until the 19th century, and we’re not even sure if it was fought in AD 633 or 634. But the significance of this clash to the future balance of power between England, Scotland and Wales cannot be overstated. Perhaps more than any battle in history, it was Heavenfield that drew the map of modern Britain.

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For all its significance, Heavenfield was not a battle that involved vast armies. This was a time when a warband of 50 men might win a kingdom. A later law code, promulgated by King Ine of Wessex in 694, defines an army as a group of 35 or more men. So it is likely that, as that most famous of Anglo-Saxon historians, Bede, writes in his account of the battle, Oswald was leading a small band of men when he confronted Cadwallon.

Bede also informs us that Oswald camped on the northern side of Hadrian’s Wall. His comrades, knowing they would face a numerically superior enemy, were relying on the tactics of surprise and assault that Oswald had learned during his years in Dál Riata (a kingdom that stretched from north-east Ireland across the North Channel to Argyll).

Ready to strike

Oswald’s aim was to attack Cadwallon before news of his presence could reach the King of Gwynedd. Near St Oswald’s Church, which commemorates the ‘heavenly field’ where Oswald and his men camped the night before the battle, archaeologists discovered the remains of one of Hadrian Wall’s milecastles. This would have made a good night camp for Oswald and his men, providing shelter and cover from eyes looking from the direction of Cadwallon’s camp.

It must have been a tense night. During the course of it, according to the account written by Adomnán, abbot of Iona from 679–704, Oswald had a dream vision of St Columba, the founder of the monastery on Iona. In the vision, the saint promised Oswald victory on the morrow. For Oswald, who had gone into exile as the pagan son of pagan Anglians, had become enchanted by the new faith of the Holy Isle. In Bede’s account Oswald also raised a cross before his warband, holding it in place while his men made it firm, then kneeling with his men to ask God’s blessing for their cause.

While he knelt there praying, Oswald would have known that he was about to pit himself against a formidable foe. Cadwallon had already defeated Oswald’s uncle, King Edwin, in battle, triggering the collapse of his nascent Northumbrian kingdom. After defeating Edwin, Cadwallon, unusually, did not return to Gwynedd. Instead he remained in Northumbria, killing two further claimants to the Northumbrian throne, Edwin’s cousin Osric and Oswald’s half-brother, Eanfrith.

Bede portrays Cadwallon as a rapacious predator, bent on destroying the Anglian kingdom of Northumbria and its people. His portrait is one-sided: for the Britons, the native people of Britain, Cadwallon was a champion, their ‘furious stag’ who broke from the mountain strongholds to which they had withdrawn to reclaim their inheritance. As such, Cadwallon’s long stay in Northumbria, which had become the pre-eminent Anglo-Saxon kingdom under the rule of King Edwin, makes some sense. Cadwallon was a Christian, a man who was still sufficiently versed in Roman culture to have a Latin epitaph carved on his father’s gravestone. But the monks of Iona, the most important spiritual centre in the Irish Sea, decided to favour their own man, Oswald, in the struggle for Northumbria. The descendants of Cadwallon, the Welsh, included in their lament for their fallen champion a veiled reference to the treachery of Iona: “From the plotting of strangers and iniquitous monks, as the water flows from the fountain, Sad and heavy will be the day for Cadwallon.”

Cadwallon’s army had been on campaign for more than a year. But his initial warband had bloated with hangers-on and the loot of many victories. Camping somewhere near the village of Corbridge, Cadwallon could guard the bridge over the river Tyne. But Oswald had advanced faster than the news of his landing could reach Cadwallon. And so, when Oswald attacked at dawn, his enemy’s camp was thrown into panic.

Bede portrays Cadwallon as a rapacious predator. But to the Britons, he was a champion who had reclaimed their inheritance

The battle turned into a series of skirmishes. Cadwallon attempted a fighting withdrawal. His end came, as Bede reports, by the Denisesburn, the Brook of Denis. While Denis Brook might have been well known in Bede’s time, its name was later forgotten, and with it the location of the battle’s climax. It was only the discovery, in the 19th century, of a 13th-century charter that made over land to Thomas of Whittington between Denisesburn and Divelis that the location was known again, for the Divelis is another name for the Devil’s Water. There Cadwallon died and Oswald claimed the Northumbrian throne.

As king, Oswald gave to the monks of Iona another island, Lindisfarne, within sight of his ancestral stronghold on Bamburgh. And with Aidan, abbot and bishop of Lindisfarne, he set about doing something that no other king of early medieval Britain had done before: create a kingdom strong enough to survive his death. The results would be momentous. Today, shaped by centuries of the political geography of Britain, we take it as read that one island should hold three nations: England, Scotland and Wales. But it was the battle of Heavenfield that played a key part in making it this way.

Furious fiery stag

By the seventh century, Anglo-Saxon kingdoms were established in the south and east of the country, but the extent of their domination was far from settled. There were natural barriers in the Pennines, and long-standing kingdoms that had weathered the first two centuries of Anglo-Saxon expansion. Imagine Cadwallon victorious. The north would have belonged to the 'furious fiery stag' who had restored the territory of the combrogi, the 'men of the same country' – the word that became Cymry. Yr Hen Ogledd, the Old North, had declined but there was still strength in it, in kingdoms such as Strathclyde. Northumbria's downfall would have allowed the expansion of these kingdoms. In what is today Scotland, the Picts and the Dál Riatans would have continued their long struggle without having to constantly guard against the Northumbrians' expansionist tendencies.

If Cadwallon had reigned for 20 years as king of Northumbria, there would probably still have been a division of the country between Anglo-Saxons, Britons, Picts and Scots, but the proportions would have been different. One can imagine an ‘England’ confined to the south and east, bounded by the Pennines and the Humber marshes or even the Wash. While this area still contains much prime agricultural land, there would have been sufficient good farmland in the rest of the country for the kingdoms of the Britons to not suffer so markedly from the economic disadvantages of being confined to unproductive areas. Fortune’s dice would not have been loaded so heavily for the English.

The battle of Heavenfield, fought between at most a few hundred men from two obscure kingdoms of early medieval Britain, set the arc of the future history of our isle. You may not have heard of it until now but, in terms of significance, it ranks right up there with Hastings.

Rival warlords

The two men who fought to the death in Heavenfield

  1. Oswald

The pious conqueror

Oswald (born 603/04) was forced into exile as a 12-year-old boy when his uncle, Edwin, killed his father, Æthelfrith, and took the kingdom of Northumbria. Oswald grew to manhood in the kingdom of Dál Riata. While there, the previously pagan Oswald embraced Christianity, and gained a reputation for martial valour and Christian piety. When Edwin was killed by Cadwallon, King of Gwynedd, Oswald remained in Dál Riata, only launching his own effort to retake the throne after Cadwallon had killed two other pretenders, both relatives of Oswald.

Victorious at the battle of Heaven-field, Oswald brought monks from Iona to preach the new religion to the Northumbrians, in the process creating institutions that were able to survive his own death in 642. A cult rapidly developed around Oswald, with the martyred king – he died in battle against the pagan king of the Mercians – becoming a popular saint in Britain and Germany.

  1. Cadwallon

The scourge of the Anglo-Saxons

So large did Cadwallon ap Cadfan (died c634) loom in the Anglo-Saxon imagination that Bede made him the principal villain of the first half of his Ecclesi- astical History of the English People. In Bede's account, the king of Gwynedd was a violent marauder, bent on exterminating the Northumbrian people. But the Britons regarded Cadwallon as their last great champion, "the fierce affliction of his foes, a lion prosperous over the Saxons".

On the isle of Anglesey, the breadbasket of Gwynedd, the kings had their palace at Aberffraw. There, Cadwallon raised a memorial stone, visible today inset into the wall of the Church of St Cadwaladr. It reads: “King Catamanus, wisest, most renowned of kings.” Catamanus is the Latin form of Cadfan, Cadwallon’s father. The brutal war-leader of Bede’s account raised a Latin inscription praising the wisdom of his father. History, as written by different sides.

Edoardo Albert is co-author, with Paul Gething, of Warrior: A Life of War in Anglo-Saxon Britain (Granta Books, 2019)


This article was first published in the December 2019 edition of BBC History Magazine