The union of Castile and Aragón
Enrique IV was the brother of Isabel. He also had a daughter
called Juana la Beltraneja, but he died and she did not
become queen.
Although she proclaimed herself Queen of Castilla in 1474,
after her brother's death, it was not until 1479, after five years
of Civil war, that Isabel was finally accepted as Queen by the
Castilian people.
Fernando was the son of the King of Aragón and he married
Isabel in 1469 . Later, in 1479,his father died and he became
King of Aragón. So the Crowns of Castile and Aragón were
united.