In 642, however, we find the two Celtic peoples at war with one another, for in that year the Britons under their king Owen defeated and slew the Scottish king Domnall Breac. In the same year they came into conflict with the Northumbrian king Oswio.
The chief of these appe a r to have been Urien, who is said to have fought against the Northumbrian king Theodoric, and Rhydderch Hen who is mentioned also in Adamnan's Life of S.
Attempt, in concert with the Northumbrian and East Anglian Danes, to conquer England.
Under Edwin the Northumbrian kingdom became the chief power in the country.
His position was assured, at least temporarily, in 617, when he decided to espouse the cause of the Northumbrian prince Edwin, then a fugitive at his court, and defeated zEthelfrith of Northumbria on the banks of the Idle, a tributary of the Trent, in Mercian territory.
The conquests of the Northumbrian kings in Cumbria were ephemeral; what Oswio won was lost after the death of Ecgfrith.
Mar never crossed the Forth, and the command of Mackintosh, who did, was captured, with his Northumbrian cavaliers, at Preston, on the very day (12th of November) when Argyll foiled Mar in the confused battle of Sheriffmuir.
He must have known, from the experience of Mercian, Northumbrian and Frankish kings, that such blackmail only bought a short respite, but the condition of his realm was such that even a moderate time for reorganization might prove valuable.
It is possible that some of the rest may be the composition of the Northumbrian herdsman; but in the absence of any authenticated example of the poet's work to serve as a basis of comparison, the internal evidence can afford no ground for an affirmative conclusion.
A copy of it, in the poet's own Northumbrian dialect, and in a handwriting of the 8th century, appears ona blank page of the Moore MS. of Beeda's History; and five other Latin MSS.