▁Alfonso . ▁Short ly ▁after ▁this , ▁Nu ño ▁left ▁for ▁the ▁service ▁of ▁King ▁Henry ▁I ▁of ▁Navar re , ▁with ▁whom ▁the ▁dis aff ected ▁nobles ▁had ▁been ▁in ▁contact ▁since ▁ 1 2 6 8 . ▁He ▁may ▁have ▁been ▁led ▁to ▁abandon ▁Cast ile ▁by ▁the ▁appro val ▁of ▁an ▁extraordinary ▁tax ▁( six ▁serv icios ) ▁by ▁the ▁cort es ▁held ▁in ▁Burg os ▁in ▁November . ▁By ▁ 1 2 7 2 , ▁Nu ño ▁he ▁had ▁entered ▁open ▁re bell ion ▁in ▁coll usion ▁with ▁Cast ile ' s ▁enemies , ▁along ▁with ▁a ▁group ▁of ▁high - ran king ▁nobles . ▁ ▁In ▁June ▁ 1 2 7 2 , ▁the ▁Mar in ids ▁inv aded ▁Cast ile ▁from ▁Mor oc co . ▁Alfonso ▁X ▁ordered ▁a ▁general ▁mobil isation , ▁sum mon ing ▁his ▁no blem en ▁to ▁appear ▁on ▁the ▁front ier ▁under ▁the ▁command ▁of ▁his ▁brother ▁Manuel ▁and ▁son ▁Fernando . ▁The ▁ref us al ▁of ▁a ▁great ▁many ▁to ▁appear ▁was ▁the ▁start ▁of ▁the ▁nobles ' ▁re bell ion . ▁The ▁leaders ▁of ▁the ▁revol t , ▁including ▁Nu ño ▁and ▁the ▁king ' s ▁brother ▁Philip , ▁had ▁been ▁in ▁contact ▁with ▁the ▁Mar in id ▁em ir , ▁Ab u ▁Y us uf , ▁and ▁his ▁son ▁Abd ▁al - W ah id . ▁Ele ven ▁letters ▁sent ▁by ▁the ▁Mar in id ▁r uler ▁and ▁his ▁son ▁to ▁the ▁re bel ▁leaders ▁were ▁intercept ed ▁by