▁and ▁stopped ▁sending ▁royal ▁en vo ys ▁to ▁the ▁Court ▁of ▁Brit t any . ▁ ▁English ▁diplom atic ▁fail ures ▁led ▁to ▁the ▁Bre ton ▁caval ry ▁command ers ▁Arthur , ▁Com te ▁de ▁Rich em ont ▁( l ater ▁to ▁become ▁Arthur ▁III , ▁Duke ▁of ▁Brit t any ) ▁and ▁his ▁nep hew ▁Peter ▁II , ▁Duke ▁of ▁Brit t any ▁playing ▁key ▁roles ▁on ▁the ▁French ▁side ▁during ▁the ▁dec iding ▁stages ▁of ▁the ▁War ▁( the ▁Battle ▁of ▁Pat ay , ▁the ▁Tre aty ▁of ▁Ar ras ▁( 1 4 3 5 ), ▁the ▁Battle ▁of ▁Form igny ▁and ▁the ▁Battle ▁of ▁Cast illon ). ▁ ▁However , ▁Brit t any ▁lost ▁the ▁Mad ▁War ▁against ▁France ▁in ▁ 1 4 8 8 , ▁mostly ▁because ▁of ▁its ▁internal ▁divisions ▁which ▁were ▁ex ac erb ated ▁by ▁the ▁cor ruption ▁at ▁the ▁court ▁of ▁Francis ▁II , ▁Duke ▁of ▁Brit t any . ▁Indeed , ▁some ▁Bre ton ▁l ords ▁were ▁fighting ▁on ▁the ▁French ▁side . ▁ ▁Union ▁with ▁the ▁French ▁Crown ▁and ▁modern ▁period ▁ ▁After ▁the ▁Mad ▁War , ▁the ▁du ke ▁Francis ▁II ▁could ▁not ▁marry ▁off ▁his ▁daughter ▁Anne ▁without ▁the ▁King ▁of ▁France ' s ▁consent . ▁Non eth eless , ▁she ▁married ▁the ▁Holy ▁Roman ▁Emperor ▁in ▁ 1 4 9 0 , ▁but ▁this ▁led ▁to ▁a ▁severe ▁crisis ▁with ▁France . ▁Charles ▁VIII ▁of ▁France ▁bes ie ged ▁R ennes ▁and ▁had ▁the ▁marriage ▁cancel led . ▁He ▁eventually