Peter III (ca. 1239-1285) was king of Aragon and count of Barcelona from 1276 to 1285 and king of Sicily from 1282 to 1285. He was one of medieval Spain's greatest rulers.

The son of King James I of Aragon and Violante (Yolanda) of Hungary, Peter (or Pedro) III inherited the crown of Aragon in 1276, after his father's extensive conquests had increased both Aragonese power and prestige. In 1262 Peter had married Constance, daughter of Manfred of Sicily and granddaughter of the emperor Frederick II, and had inherited in 1266 the Hohenstaufen family claim to the kingdom of Sicily. Aragon's geographical and economic orientation toward the Mediterranean, Aragonese claims on the kingdom of Sicily, and Peter's great personal abilities made him the first monarch in the Spanish peninsula to participate actively and successfully in the wider affairs of Europe and the Mediterranean.

At the beginning of his reign Peter committed his resources to the construction of a large fleet and the assemblage of a formidable military force. His first target for expansion was the kingdom of Tunis, in whose internal affairs the kings of Aragon had long had an interest. He concerned himself for 6 years with the exploitation of political rivalries among the Moslem rulers of North Africa, but his interest in Aragonese expansion into the Mediterranean did not end there. The crisis in Sicilian politics that occurred between 1266 and 1282 offered him an opportunity to intervene. In 1266 Charles of Anjou, the brother of King Louis IX of France, had defeated the last of the Hohenstaufen rulers of Sicily and, with papal support, had been named king of Sicily. Charles's rule had been harsh; his ambitions had extended to the control of the papacy and the conquest of the Byzantine Empire; and his French nobles and military garrisons had outraged the people of Sicily. In 1282 the population of the island rose up and massacred the French garrisons (the "Sicilian Vespers"), and after a brief period of independence they offered the crown of the kingdom to Peter III because he was the husband of Constance, the last member of the Hohenstaufen family.

Peter's reign in Sicily was challenged by Charles of Anjou, the papacy, and Charles's nephew King Philip III of France. The power of the Aragonese and Sicilian fleets, under the command of the brilliant admiral Roger of Loria, maintained the integrity of the island and confined Charles's forces to the mainland portion of the kingdom in southern Italy. Upon Charles's death in 1285, Philip III invaded Aragon, stirring up a revolt against Peter by Aragonese who resented their King's overseas preoccupations. Philip also played upon the resentment felt toward Peter by his brother King James I of Majorca. Philip, however, died later in 1285, and Peter drove the French from Aragon shortly before he died on Nov. 11, 1285.

In addition to his considerable achievements in North Africa and Sicily, which laid the base for later Aragonese expansion into the eastern Mediterranean, Peter faced the difficulties of a divided kingdom and the wide resentment against his overseas enterprises. In 1283 the nobles and cities of Aragon demanded that he recognize their liberties and cease his demands for unusual fiscal grants. Peter responded with the famous General Privilege, sometimes called the "Magna Carta of Aragon, " a gesture that conciliated his subjects and restored his prestige. His career thus represented both the extension of Aragonese influence in the Mediterranean world and the peaceable definition of the terms according to which king and subjects recognized the limits of their powers in Aragon.

Further Reading on Peter III

There is no biography of Peter III in English. Excellent accounts of his reign are in Roger Bigelow Merriman, The Rise of the Spanish Empire in the Old World and the New, vol. 1 (1918), and Sir Stephen Runciman, The Sicilian Vespers (1960). A good example of Peter's subsequent popularity may be seen in the 14th-century work by Ramón Muntaner, The Chronicle of Muntaner (trans., 2 vols., 1920-1921).