Philip I of Castile

Philip I of Castile married Joanna of Castile, the daughter of Ferdinand II of Aragon and Isabella I of Castile. This marriage was part of a double alliance between Spain and the Habsburgs, strengthening ties between the two dynasties and eventually bringing the Spanish throne to the Habsburg family.

Upon the death of Isabella I of Castile, Philip I and Joanna became the nominal rulers of Castile. However, Ferdinand II of Aragon disputed their claim, leading to a power struggle. Philip traveled to Castile to assert his authority, but his reign was brief.

Philip I of Castile and Ferdinand II of Aragon signed the Treaty of Villaf

Philip I of Castile died suddenly at the age of 28 in Burgos, possibly from typhoid fever or poisoning. His death left Joanna as the sole ruler of Castile, but her mental instability led to her confinement and the eventual assumption of power by her father Ferdinand II.