GUGLIELMO of TIRO. - He probably belonged to an Italian family, perhaps Roman, but he was born in Jerusalem around 1130–35. He pursued his literary and theological studies in the West: his broad classical culture is demonstrated by the many references to ancient writers found in his work. He also knew Greek and Arabic. Around 1160 he reappeared in Jerusalem at the court of King Amaury I, who held him in high esteem and made him a canon and then archdeacon of the church of Tiro; he subsequently became tutor to Baldovino who, upon becoming king in 1174, made him his chancellor and in 1175 secured for him the archiepiscopal see of Tiro. He played a considerable part in the political life of the Kingdom: he was repeatedly ambassador to Constantinople and also to Rome, where he later went for the Council of 1179.
The last documentary record of him dates from 1185, but he was still alive in 1184. His principal work is the Historia verum in paribus transmorinis gestarum in 23 books, which, however, remained unfinished. It is a truly monumental work: in its first books it synthesizes what had been supplied by historiographical tradition concerning the First Crusade; thereafter it is an original and authoritative source. Balanced in
