Guerra de Sucesión Castellana
Castile had traditionally had good relations with the neighboring Kingdom of Portugal, and after the Portuguese lost the War of the Castilian Succession, Castile and Portugal concluded the Treaty of Alcáçovas. The treaty set boundaries for overseas expansion which were at the time disadvantageous to Castile, but the treaty resolved any further Portuguese claims on the crown of Castile. Portugal did not take advantage of Castile's and Aragon's focus on the reconquest of Granada. Following the reestablishment of good relations, the Catholic Monarchs made two strategic marriages to Portuguese royalty.