John of Ibelin, count of Jaffa (1246/1247-1266), was the author of a famous treatise on the laws and customs of the High Court of the kingdom of Jerusalem, known simply as Livre de Jean d’Ibelin.
Written in Old French in the 1260s, John’s treatise provides by far the most detailed account of court procedures and the laws of vassalage and fief-holding in Outremer. What would today be termed an appendix has details of the coronation ritual, the functions of the great officers of state, the structure of the ecclesiastical hierarchy, the location of the secular courts, and the military obligations of the kingdom as they existed on the eve of its collapse in 1187. In 1369 a version of the treatise was made an official work of reference in the High Court of Cyprus, and in the sixteenth century the Venetian authorities in the island had it translated into Italian.
As the son of Philip of Ibelin, regent of Cyprus in the 1220s, John was the leading representative of the cadet branch of the Ibelin family. Too young to play much part in the civil war in Cyprus in 1229-1233, John soon established himself as a prominent vassal of King Henry I (1218-1254). Indeed, he and Henry both married sisters of King Het‘um I of Cilicia. In 1246 or 1247 Henry gave John the county of Jaffa in Palestine, property that had been his mother’s dower, and John thereafter employed the title “count of Jaffa and Ascalon and lord of Ramla” until his death. John never seems to have had possession of Ascalon (mod. Tel Ashqelon, Israel), which was lost to the Muslims in 1247, but the cost of defending Jaffa (mod. Tel Aviv-Yafo, Israel) proved crippling. He nevertheless played the part of a leading aristocrat: the French chronicler John of Joinville, for example, commented on the conspicuous display of his coat of arms both at Damietta in 1249, during the crusade of Louis IX of France, and at Jaffa.
In the mid-1250s John was briefly bailli (regent) in Acre (mod. ‘Akko, Israel), acting nominally on behalf of the absentee king, Conrad of Staufen. In 1258 he intervened decisively in the War of St. Sabas to bring the government in Acre over to the side of the Genoese. At about the same time he appears to have taken Plaisance of Antioch, Henry I’s widow and the mother of the infant King Hugh II, as his mistress.
In the closing years of John’s life, the Mamlûk sultanate under Baybars I (d. 1277) was growing in power, and in 1268, just over a year after his death, Jaffa was taken by assault. John’s descendants thereafter lived in Cyprus, where they held important estates, including Episkopi and Peristerona in Morphou. The line appears to have died out in the 1360s.