▁or ▁two . ▁ ▁The ▁treat y ▁Mal col m ' s ▁ra iding ▁of ▁northern ▁England ▁and ▁the ▁formal ▁link ▁between ▁the ▁royal ▁house ▁of ▁Scotland ▁and ▁the ▁Ang lo - S ax on ▁house ▁of ▁W esse x ▁was ▁an ▁obvious ▁threat ▁to ▁William . ▁With ▁his ▁campaign ▁in ▁the ▁north ▁country ▁over , ▁he ▁turned ▁his ▁attention ▁to ▁Scotland . ▁In ▁ 1 0 7 2 ▁he ▁brought ▁an ▁army , ▁consisting ▁of ▁kn ights ▁cl ad ▁in ▁chain ▁mail ▁mounted ▁on ▁fast ▁horses , ▁into ▁southern ▁Scotland . ▁He ▁des patch ed ▁a ▁fleet ▁of ▁ships ▁up ▁the ▁Scottish ▁eastern ▁coast , ▁to ▁provide ▁supplies ▁for ▁his ▁troops ▁adv ancing ▁on ▁land . ▁William ▁crossed ▁the ▁For th ▁and ▁at ▁an ▁eng agement ▁near ▁A bern eth y ▁in ▁Per th shire ▁he ▁defeated ▁Mal col m ' s ▁forces , ▁who ▁were ▁no ▁match ▁for ▁the ▁Norman ▁army . ▁William ▁forced ▁Mal col m ▁to ▁sign ▁the ▁ ▁Tre aty ▁of ▁A bern eth y ▁ ▁through ▁which , ▁according ▁to ▁the ▁Ang lo ▁Sax on ▁Chron icle , ▁Mal col m ▁became ▁" Will iam ' s ▁man ". ▁The ▁full ▁details ▁of ▁the ▁treat y ▁are ▁not ▁known ▁as ▁no ▁documents ▁have ▁surv ived , ▁but ▁it ▁seems ▁that ▁Mal col m ' s ▁son ▁Dun can ▁was ▁given ▁as ▁host age ▁and ▁Ed gar ▁was ▁exp elled ▁from ▁the ▁Scottish ▁court . ▁In ▁return ▁for ▁swe aring ▁alleg iance ▁to ▁William , ▁Mal col m