The Ottoman conquest that brought the demolition of Catholic churches and the islamization of the population, almost completely destroyed the presence of the Catholic Church in these areas, with the exception of southern regions around Livno. City of Bihać resisted the longest, until 1591. From the time of the Ottoman conquest, the pastoral clergy in these parts were almost exclusively Bosnian Franciscans. On the Livno area was recorded the presence of Glagolitic Catholic secular priests who celebrated the Slavic liturgy. The bishops did not dare to come to parts of their dioceses that fell under Turkish rule. That is why, in 1735, instead of the existing dioceses, the Holy See founded the Apostolic Vicariate in Ottoman Bosnia ("Vicariatus Apostolicus Bosniae Othomanae"). The Catholic church in Banja Luka was particularly hard hit during the War of the Holy League (1683-1699). In 1737 parish church in Banja Luka was burned and numerous believers migrated to the Habsburg possessions.