See also: Roman Catholicism in Ukraine and Latin Cathedral, Lviv. The Latin Church Archdiocese of Lviv was erected on August 28, 1412 in the city of Lwów (today Lviv). It serves as a metropolitan see of the Roman Catholic Church in Ukraine. The principal patron of the Archdiocese is the Blessed Virgin Mary Mother of Mercy.
In 1909 Pope Pius X proclaimed the Blessed Virgin Mary, Queen of Poland and Blessed Jakub Strzemię to be the patrons of the Lviv archdiocese. In 1910 the Blessed Virgin Mary, Queen of Poland became the principal patron. Nowadays the principal patron is the Blessed Virgin Mary Mother of Mercy (NMP Łaskawa). The patron's day is celebrated on 1 April, the day when King of Poland Jan II Kazimierz Waza took an oath at the Lwów Cathedral in 1655, during "The Deluge," took vows of loyalty to God and declared the Mother of God to be the Queen of Poland.
In 1414 a metropolitan see was moved from Halych to Lviv. Diocese of Halicz was merged with diocese of Lwow.
An attempt to liquidate the Catholic Church in Ukraine was made with the start of World War II in 1939 and partition of Poland between Nazi Germany and Soviet Union. After World War II and until fall of the Soviet Union, the Archdiocese of Lwów was centered in Lubaczów.