Frederick II (or
III) (13 December 1272 – 25 June 1337) was the
regent (from 1291) and subsequently King of
Sicily from 1295 until his death. He was the third son of
Peter III of Aragon and served in the
War of the Sicilian Vespers on behalf of his father and brothers,
Alfonso and
James. He was confirmed as King of
Trinacria (another name for the island of Sicily) by the
Peace of Caltabellotta in 1302. His reign saw important constitutional reforms: the
Constitutiones regales,
Capitula alia, and
Ordinationes generales.