How did Franciscan missionaries affect the Bosnian church during the 14th and 15th centuries?

During the 14th and 15th centuries, the Roman Catholic Franciscans played a pivotal role in the religious landscape of medieval Bosnia. Beginning in 1340, they established a network of friaries and engaged in a long-term campaign to convert members of the Bosnian church to mainstream Catholicism, as the official view from Rome held that the Bosnian church had fallen into heresy.1

The Franciscans' influence culminated in 1459, when the Bosnian king, Stjepan Tomaš Ostojić, provided full support for their mission. He issued an order requiring the clergy of the Bosnian church to either convert to Roman Catholicism or depart from the kingdom. When the majority of the clergy chose to convert, the organizational structure of the Bosnian church was effectively broken.1

While some historical accounts previously labeled the Bosnian church as dualist heretics, modern scholarship suggests it was an essentially nonheretical branch of the Roman Catholic Church that had developed unique practices due to its isolation.1