III., king of Aragon (1236-1286), son of James the Conqueror, and his wife Yolande, daughter of Andrew II. of Hungary, was born in 1236. Having married Constance, daughter of Manfred of Beneventum, he came forward as the representative of the claims of the Hohenstaufen in Naples and Sicily against Charles, duke of Anjou. Peter began the long strife of the Angevine and Aragonese parties in southern Italy. His success in conquering Sicily earned him the surname of "the Great." He repelled an invasion of Catalonia undertaken by the king of France in support of Charles of Anjou, and died on the 8th of November 1286.
For the personal character of Peter III., the best witness is the Chronicle of Ramonde Muntanez - reprinted in the original Catalan by R. Lanz, Literarischer Verein in Stuttgart, vol. vii. (1844), and in French by Buchon, Coll. des chroniques nationales (Paris, 1824-1828). See also O. Cartellieri, Peter von Aragon and die Sizilianische Vesper (Heidelberg, 1904).