At the commencement of the battle, Bede tells us that the pagan Æthelfrith slaughtered 1200 monks from the important monastery of Bangor-on-Dee in Maelor because, he said, "they fight against us, because they oppose us by their prayers".
Ved kampenes begyndelse fortæller Beda at den hedenske Æthelfrith slagtede 1200 munke fra det vigtige kloster i Bangor-on-Dee i Maelor fordi, skrev han, "de kæmper mod os fordi de modsætter sig os med deres bønner".