Specifically, the death of his half-brother Edwin in 933 might have finally removed factions in Wessex opposed to his rule, while Guthfrith, the Norse king of Dublin who had briefly ruled Northumbria, had died in 934, meaning that any resulting insecurity among the Danes would have given Æthelstan an opportunity to stamp his authority on the north.
A second theory concerns an entry in the Annals of Clonmacnoise, recording the death in 934 of a ruler who was possibly Ealdred of Bamburgh.
[4] By late June or early July the army had reached Chester-le-Street, where Æthelstan made generous gifts to the tomb of Cuthbert, including a stole and maniple (ecclesiastical garments) originally commissioned by his step-mother Ælfflæd as a gift to Bishop Frithestan of Winchester.
According to the twelfth-century chronicler Simeon of Durham, his land forces ravaged as far as Dunnottar and Fortriu in northern Scotland, while the fleet raided Caithness by which a much larger area, including Sutherland, is probably intended.
[6] The Annals of Clonmacnoise state that "the Scottish men compelled [Æthelstan] to return without any great victory", while Henry of Huntingdon claims that the English faced no opposition.