 Henry VII planned to marry Arthur to a daughter of the Catholic Monarchs , Isabella I of Castile and Ferdinand II of Aragon , in order to forge an Anglo @-@ Spanish alliance against France . It was suggested that the choice of marrying Arthur to Ferdinand and Isabella 's youngest daughter , Catherine ( b . 1485 ) , would be appropriate . The Treaty of Medina del Campo ( 27 March 1489 ) provided that Arthur and Catherine would be married as soon as they reached canonical age ; it also settled Catherine 's dowry at 200 @,@ 000 crowns ( the equivalent of £ 5 million in 2007 ) . Since Arthur , not yet 14 , was below the age of consent , a papal dispensation ( i.e. , waiver ) allowing the marriage was issued in February 1497 , and the pair were betrothed by proxy on 25 August 1497 . Two years later , a marriage by proxy took place at Arthur 's <unk> Manor in Bewdley , near Worcester ; Arthur said to Roderigo de Puebla , who had acted as proxy for Catherine , that " he much rejoiced to contract the marriage because of his deep and sincere love for the Princess " . 
