He also spread the terror of the Saxon arms to the neighbouring people, and by his victories over the Scots and Picts, as well as Welsh, extended on all sides the bounds of his dominions.

Having laid siege to Chester, the Britons marched out with all their forces to engage him, and they were attended by a body of 1250 monks from the monastery of Bangor, who stood at a small distance from the field of battle, in order to encourage the combatants by their presence and exhortations.
Adelfrid, inquiring the purpose of this unusual appearance, was told, that these priests had come to pray against him: THEN ARE THEY AS MUCH OUR ENEMIES, said he, AS THOSE WHO INTEND TO FIGHT AGAINST US [l]: and he immediately sent a detachment, who fell upon them, and did such execution, that only fifty escaped with their lives [m].

The Britons, astonished at this event, received a total defeat; Chester was obliged to surrender; and Adelfrid, pursuing his victory, made himself master of Bangor, and entirely demolished the monastery, a building so extensive that there was a mile's distance from one gate of it to another, and it contained two thousand one hundred monks, who are said to have been there maintained by their own labour [n].
[FN [l] Brompton, p.779.

[m] Trivet, apud Spell.Conc.p.111.

[n] Bede, lib.2.cap.2.