TREBISONDA (TRAPEZUNTE, TRABZON). — The Greek bishopric of T., later elevated to a metropolitan see, already existed at the time of the Council of Nicaea (325).
Under Diocletian, St. Eugenio, the future patron of the city, died there as a martyr. The development of Christian life was manifested in the foundation of numerous monasteries and famous churches. The bishops of T. took part in the ecumenical Councils and in those of Constantinople. The bishopric followed the fate of Constantinople in the schism of the 11th century. After the erection of the small empire of T. by the Comneni in the 13th century, the city could no longer attain the power it had possessed when it formed part of the Byzantine Empire. Nevertheless, T. cultivated relations on several occasions, through treaties, with the Western powers and with Venice, Genoa, and Florence, and sought support in the West, including from the Pope, when in the 15th century its very existence was threatened by the Turks, who destroyed the Empire of T. in 1461 (v. ORANTE, IMPERO D. II. Impero latino d'Oriente).
The Latin bishopric of T. was erected in 1314, but as early as the 15th century it became merely titular. A Franciscan convent is attested from the year 1314; it still existed in 1390; the same is known of a Dominican monastery. Later, in 1652, the Capuchins attempted to exercise their apostolate from their mission in Georgia, but only in 1845 could the mission of T. be established, together with the nearby cities of Sinope and Samsun; the superior of the mission was granted the faculties of an apostolic prefect. Later, the Mechitarists and the Jesuits under Leo XIII came to the aid of those regions, as did the Sisters of St. Joseph and the Armenian Sisters. The tragic events that befell the Armenians in 1895 and during the First World War (1914–18), together with the forced emigration of Christians from the regions around the Black Sea, were highly disastrous for the apostolic prefecture of T., which became a simple mission after the decree of 12 September 1896 abolishing the Prefectures of the Apostolic Missions among the Eastern Churches. On 20 June 1931, a mission « sui iuris » was created at T. for the faithful of the Latin rite (AAS, 23 [1931], pp. 402–403), entrusted to the Capuchins.
The Catholic diocese of the Armenian rite (erected in 1850) was already vacant, impeded, and dispersed in 1932.
Among the distinguished figures of T. are remembered Cardinal Bessarione, who wrote an Encomio in honour of his native city, published by Spyr. Lampros in the journal Νέος Ἐλληνομένων, 13 (1916), pp. 145–204. At the Council of Florence, the metropolitan Dorotheo signed the bull of Union. In the first half of the 17th century, the metropolitan Cirillo embraced union with the Catholic Church and was therefore expelled from his see (v. C. Giannelli, in Orientalia Christ. Periodica, 15 [1949], p. 167 ff). Papal letters addressed to the Emperors of T., still preserved, date from the years 1291, 1329, 1434, and 1460. The abbot of the Mechitarists of Venice, Ignazio Ghiurekean, a native of T., also rendered great service to T. by founding a school there in 1876.