Florence, Church Union of. A union of the Eastern and the Western (Roman Catholic) churches concluded at the Church Council of Florence in 1439. The Byzantine emperor John VIII Palaeologus was eager for a union for political reasons (the Turkish threat), and there were those among the Greek hierarchy who wanted a union for religious reasons (Patriarch Joseph II and Archbishop Bessarion of Nicaea). The expected military aid from the West against the Turks was not forthcoming, however; hence, the Union of Florence, which meant submission to Rome's authority, was badly received by the citizens of Constantinople and most of the Orthodox world.
The Kyivan metropolitan Isidore, who was of Greek descent and who represented the Church of Rus’ at the Ferrara-Florentine Council, was a prominent advocate of the Union of Florence. On his return to Moscow (the seat of Kyiv metropoly at the time), Isidore met with opposition to the union from the Muscovite grand prince Vasilii II and the clergy. Nor did his efforts gain any support among the Polish hierarchy. Only the Kyiv prince Olelko Volodymyrovych favored the union. Lacking wider support, Isidore left Rus’ and returned to Rome, where he became a cardinal. One important consequence of the union was the division of Kyiv metropoly into a Muscovite and a Ukrainian-Belarusian metropoly. The union was partly in force in the latter until 1501. The conditions of this union became the basis of the Church Union of Berestia in 1596.
[This article originally appeared in the Encyclopedia of Ukraine, vol. 1 (1984).]
Encyclopedia of Ukraine