The Ukrainian Greek Catholic Church (UGCC) is a major archiepiscopal sui iuris ("autonomous") Eastern Catholic church that is based in Ukraine. As a particular church of the Catholic Church, it is in full communion with the Holy See. It is the second-largest particular church in the Catholic Church after the Latin Church. The major archbishop presides over the entire Church but is not distinguished with the patriarchal title. The incumbent Major Archbishop is Sviatoslav Shevchuk. The church regards itself as a successor to the acceptance of Christianity by Grand Prince Volodymyr the Great, the founder of the medieval state of Kievan Rus'. The foundation of the Orthodox Church in Rus' is traditionally dated to 988 AD. In 1596, by the terms of the Union of Brest, this Rus' or Ruthenian Church transferred from the ecclesiastical jurisdiction of the Ecumenical Patriarchate of Constantinople to the jurisdiction of the Holy See, thereby forming the Ruthenian Uniate Church. The "Union of Brest" was a treaty between the Ruthenian Orthodox Church in the Polish–Lithuanian Commonwealth, under the leadership of the Metropolitan of Kyiv, Galicia and All Ruthenia — Michael III — on one part, and the Latin Church under the leadership of Pope Clement VIII on the other part.Following the partitions of Poland, the eparchies of the "Ruthenian Uniate Church" (Latin: Ecclesia Ruthena unita) were liquidated in the Russian Empire and the Kingdom of Prussia. Only the three eparchies that came under Austrian jurisdiction remained of the Brest Union. In 1963, the church was recognized as Ukrainian through the efforts of Yosyf Slipyi. In 1963, the ordinary (or hierarch) of the church was granted the title of "Major Archbishop". He currently holds the title of "Major archbishop of Kyiv-Galicia". However, the hierarchs and faithful of the church acclaim their ordinary as "Patriarch" and have requested Papal recognition of this honour. Source: Wikipedia (en)