Friar Dolcino, the founder of a society called the Apostelic Bretheren in 1260, was condemned as a 'treacherous heretic' and was persecuted by the Catholic Church for his heretical teachings and writings during the early 14th century, most notably his claim that authority had passed from the Roman Church to the Bretheren. This persecution culminated in an almost year-long siege at Monte Rubello near the Italian town of Trivero which led to Dolcino's eventual surrender in March 1307 and his burning as a heretic shortly after. This study examines the events of 1305-7, the church's crusade against heretics and against Dolcino specifically, and describes and analyses the siege as it unfolded and the final battle that took place. Italian text.