The controversy between Orthodox and Catholics in Ukraine is rooted in the historical conflict between Ukrainian Cossacks and Polish gentry in medieval times.
The trouble started after Poland’s King Zygmunt III, a devout Roman Catholic, allowed Jesuit monks into Latvia and Ukraine to convert the Orthodox population to the Catholic faith. Together with Jesuit Pope Climent VIII, the Polish king sought to create a union of Roman Catholic and Greek Orthodox Churches – a union that eventually led to the formation of the Greek Orthodox Church.
The Greek Catholic Church’s mass, language and calendar remained identical to that of the Orthodox Churches. The only difference was that the new entity fell under Rome’s direct supervision.
After some Ukrainian Orthodox clergy became dissatisfied with the leadership of patriarchs based in Constantinople and after Zygmunt enticed them with privileges, many clerics signed the Union of Brest in 1596.
The Polish king then declared the terms of the union obligatory for all Orthodox believers living on Polish territory. The move ultimately made the Orthodox Church illegal in Ukraine, forcing it underground.
Some Ukrainians opposed the union, feeling that it was being established by force and that it was a ploy to bolster Poland’s influence in the region. The Union of Brest became a primary reason for an anti-Polish uprising by the Cossacks between 1591 and 1596.
The Cossack rebellion resulted in a number of bloody massacres in which many members of the Polish gentry, along with Ukrainian supporters of the new church union, were killed and their property destroyed.
Severyn Nalyvaiko became a well-known Cossack leader, fighting Zygmunt and his union. Backed by an army of 3,000, Nalyvaiko battled Ukraine’s Polish rulers for years until ultimately meeting defeat near the town of Lubny in 1596. He was subsequently taken to Warsaw and publicly beheaded.
Cossack-led uprisings against the Poles lasted until 1654, when Hetman Bohdan Khmelnystky signed a treaty with Russia.
