▁North umb ria ▁who ▁had ▁been ▁ban ished ▁by ▁Edward ▁the ▁Conf essor ), ▁was ▁a ▁native ▁of ▁North umb ria ▁and ▁his ▁family ▁had ▁a ▁history ▁of ▁being ▁r ul ers ▁of ▁Bern icia , ▁and ▁at ▁times ▁North umb ria . ▁Cop si ▁had ▁fought ▁in ▁Har ald ▁Hard r ada ' s ▁army ▁with ▁T ost ig , ▁against ▁Harold ▁God win son ▁at ▁the ▁Battle ▁of ▁St am ford ▁Bridge ▁in ▁ 1 0 6 6 . ▁He ▁had ▁managed ▁to ▁escape ▁after ▁Har ald ' s ▁defeat . ▁When ▁Cop si ▁offered ▁hom age ▁to ▁William ▁at ▁B ark ing ▁in ▁ 1 0 6 7 , ▁William ▁reward ed ▁him ▁by ▁making ▁him ▁ear l ▁of ▁North umb ria . ▁After ▁just ▁five ▁weeks ▁as ▁ear l , ▁Cop si ▁was ▁murder ed ▁by ▁Os ulf , ▁son ▁of ▁Earl ▁E ad ulf ▁III ▁of ▁Bern icia . ▁When , ▁in ▁turn , ▁the ▁us ur ping ▁Os ulf ▁was ▁also ▁killed , ▁his ▁cousin , ▁C osp atr ick , ▁bought ▁the ▁ear ld om ▁from ▁William . ▁He ▁was ▁not ▁long ▁in ▁power ▁before ▁he ▁joined ▁Ed gar ▁ Æ th eling ▁in ▁re bell ion ▁against ▁William ▁in ▁ 1 0 6 8 . ▁ ▁With ▁two ▁ear ls ▁murder ed ▁and ▁one ▁changing ▁sides , ▁William ▁decided ▁to ▁interven e ▁personally ▁in ▁North umb ria . ▁He ▁march ed ▁north ▁and ▁arrived ▁in ▁York ▁during ▁the ▁summer ▁of ▁ 1 0 6 8