Northumbria falls into disarray after the slaying of Edwin, with Eanfrith returning from Pictland to take power in the subkingdom of Bernicia and …

…Osric taking power in Deira.

Osric according to Bede, was, like Eanfrith, a Christian who reverted to paganism upon coming to power.

James, the deacon of Bishop Paulinus of York, remains in the north following Edwin’s death; he will struggle to rebuild the Roman mission.

Paulinus himself has fled with queen Æthelburga and her young daughter Eanflæd south to Kent, where he is made bishop of Rochester.

Eanflæd will grow up under the protection of her uncle, king Eadbald of Kent.

It is possible that Eanfrith had been initially cooperative with Cadwallon.

The historian D. P. Kirby, pointing to Eanfrith's evident ability to quickly exploit Edwin's death, has speculated that "a wide-ranging set of alliances" that included both Cadwallon and Eanfrith may have existed. (Kirby, The Earliest English Kings (1991, 2000), page 73.)

If there was a friendly relationship between Eanfrith and Cadwallon at first, however, it must not have lasted, since Bede reports that Eanfrith went to Cadwallon "with only twelve chosen soldiers" in an attempt to negotiate peace, but Cadwallon had him killed.

Edwin’s nephew Oswald of Bernicia (Eanfrith's brother), exiled for the past eighteen years in Dál Riata, sees an opportunity to recover his father’s throne.

Accompanied possibly by a force of Scots (or Picts), Oswald defeats and kills Cadwallon with a Welsh army near Hexham (Northern England) in the Battle of Heavenfield.

He reunites Deira with Bernicia, and becomes king of Northumbria.

The year in which Eanfrith and Osric have ruled will subsequently be deemed so abhorrent because of their paganism that it will be decided to add that year to the length of the reign of the Christian King Oswald, so as to ignore the brief reigns of the polytheist Eanfrith and Osric.

Cadwallon, besieged by king Osric at York, successfully breaks out of the city with all his forces, by surprise, and destroys Osric and his army.