The same sources appear to reveal that Æthelstan was supported on his campaign by the Welsh potentates Hywel Dda, Idwal Foel, King of Gwynedd, and Morgan ab Owain, King of Gwent. The fullest account of the English campaign is preserved by the twelfth-century Historia regum Anglorum, a source which states that Æthelstan's land forces marched as far as Dunnottar and , and that his maritime forces reached as far as  (seemingly Caithness). According to the twelfth-century Libellus de exordio, Owain and the Cumbrians were caught up in campaign, with Owain and his Scottish counterpart, Custantín, being put to flight by Æthelstan's forces.
The same sources indicate that Æthelstan was supported during his expedition by Welsh leaders Hywel Dda, Idwal Foel (King of Gwynedd), and Morgan ab Owain (King of Gwent). The Historia regum Anglorum, a twelfth-century account, states that Æthelstan's land forces marched as far as Dunnottar and , while his naval forces reached as far as  (possibly Caithness). According to the Libellus de exordio, Owain and the Cumbrians were part of the campaign, with Owain and Custantín being defeated by Æthelstan's troops.