A turning point in the Bulle's history was during the Burgundian Wars. On 16 January 1476 it entered into an alliance with the city of Fribourg. Due to the treaty, it was not plundered by the victorious Swiss after the Battle of Morat (22 June 1476). In 1536, as the Bernese conquered the Vaud, Bishop Sébastien de Montfalcon fled from Lausanne to Fribourg and placed himself and Bulle under the protection of that city. With Fribourg's protection, Bulle was able to remain Catholic. However, the protection of Fribourg was transformed into domination in 1537. The citizens were placed under a Fribourg appointed bailiff who ruled over the former episcopal lands from the castle in Bulle.