Frederick III (also Frederick II, ', ', '); 13 December 1272 – 25 June 1337) was the regent of the Kingdom of Sicily from 1291 until 1295 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 ΙΙΙ and James ΙΙ. He was confirmed as king by the Peace of Caltabellotta in 1302. His reign saw important constitutional reforms: the Constitutiones regales, Capitula alia, and Ordinationes generales.
Name
Although the second Frederick of Sicily, he chose to call himself "Frederick III" (being one of the rare medieval monarchs who actually used a regnal number) – presumably because only some fifty years before, his well-known and remembered great-grandfather had ruled Sicily and also used an official ordinal: Fridericus secundus, imperator etc.. Thus, Fridericus tertius was better in line with the precedent of his ancestor's ordinal. However, an anecdote attributes Frederick's choice of numeral to him being the third son of Peter. The next man called Frederick to occupy the Sicilian throne was dubbed by later generations of historians as Frederick III: Frederick the Simple, though he himself did not use an ordinal.
Biography
Early years
Frederick was born in Barcelona.
When his father died in 1285, he left the Kingdom of Aragon to his eldest son, Alfonso, and that of Sicily to his second son, James. When Alfonso died in 1291, James became king of Aragon and left Frederick as regent in Sicily. The war between the Angevins, who contested the title to Sicily from their peninsular possessions centred on Naples (the so-called Kingdom of Naples), and the Crown of Aragon for the possession of the island was still in progress, and although the Crown of Aragon was successful in Italy, James’ position in Spain became very insecure due to internal troubles and French attacks. Peace negotiations were begun with Charles II of Naples, but were interrupted by the successive deaths of two popes. At last, under the auspices of Pope Boniface VIII, James concluded a treaty, by which, in exchange for being left undisturbed in the rest of the territories belonging to the Crown of Aragon and promised possession of Sardinia and Corsica, he gave up Sicily to the Church, for whom it was to be held by the Angevins (Treaty of Anagni, 10 June 1295). The Sicilians refused to be made over once more to the hated French they had expelled in 1282 (in the Sicilian Vespers), and found a national leader in the regent Frederick. In vain the pope tried to bribe him with promises and dignities; he was determined to stand by his subjects, and was crowned king by the nobles at Palermo in 1296.
When Frederick heard that James was preparing to go to war with him, he sent a messenger, Mountainer Pérez de Sosa, to Catalonia in an effort to stir up the barons and cities against James in 1298. Mountainer carried with him an Occitan poem, Ges per guerra no.m chal aver consir, intended as a communication with his supporters in Catalonia. This communiqué seems to have had in mind Ponç Hug as a recipient, for the count penned a response (under the title con d'Empuria), A l'onrat rei Frederic terz vai dir, in which he praised Frederick's tact and diplomacy, but told him bluntly that he would not abandon his sovereign.