Juan Manuel had constant confrontations with his king. At the time, the throne of Castile was occupied by two monarchs, Ferdinand IV and Alfonso XI. Juan Manuel's loyalty was with Alfonso, to whom Juan Manuel gave the hand of his daughter Constanza. The wedding was postponed several times, until finally Alfonso XI jailed Constanza in the Castle of Toro for unclear reasons. This incident angered Juan Manuel, who decided to turn against Alfonso. He declared war on Alfonso, beginning a long confrontation.