Headed the first secession of the Welsh Marchers from the party of the opposition (1263), and was amongst the captives whom the Montfortians took at Lewes.
Hence the extraordinary slowness of their manoeuvres, not because the Austrian infantry were bad marchers, but because the preparation and circulation of orders was still far behind the French standard.
But he never desisted from his wars with the Marchers of South Wales, and in the early years of Henry III.
Thus, in the reign of Alexander, the fugitive serfs whom tyranny or idleness had driven into this wilderness (they were subsequently known as Kazaki, or Cossacks, a Tatar word meaning freebooters) were formed into companies (c. 1504) and placed at the disposal of the frontier starostas, or lord marchers, of Kaniev, Kamenets, Czerkask on the Don and other places.
A licence to enlist allies among the Welsh marchers, Dermot secured the aid of the Clares and Geraldines.
The old Welsh land tenure by gavelkind was, however, still permitted to remain in force amongst the natives of all Wales, whilst it was henceforth arranged to administer justice in the eight counties by special royal judges, and in the Marches by the officers appointed by the various lords-marchers according to the terms of their tenure.
In vain did Henry and his lords-marchers endeavour to suppress the rebellion, and to capture, by fair means or foul, the person of Glendower himself; the princely adventurer seemed to bear a charmed existence, and for a few years Owen was practically master of all Wales.
To the east of it, the Navarrese, having rid themselves of the Carolingian counts and marchers, had made a kingdom in their mountains, and beyond them the little free territorias of the central Pyrenees were advancing, in subordination to the Navarrese king at Pamplona.
With the object of suppressing private feuds and other illegalities amongst the lords-marchers and their retainers.