After their humiliation at Kypsela, Theodor-Peter and Asen returned to their homeland and decided to incite a rebellion. A formal speech, delivered in praise of Isaac II in 1193, stated that Theodor-Peter had been the "first to rebel" against the emperor. Madgearu notes that Michael Choniates describes Theodor-Peter as a "hateful and renegade slave", which also suggests that he was the instigator of the uprising. The brothers knew that the collection of an extraordinary tax, which had been levied in the autumn of 1185, angered the population, especially in the region of Anchialos (now Pomorie in Bulgaria). However, they could not provoke the discontented people into rebellion initially because their compatriots looked "askance at the magnitude of the undertaking", according to Choniates. Theodor-Peter and Asen decided to take advantage of the Bulgarians and Vlachs' devotion to the cult of the martyr saint Demetrius of Thessaloniki to persuade them to rise up against the Byzantine rule. Theodor-Peter and Asen built a "house of prayer" dedicated to the saint and gathered Bulgarian and Vlach prophets and prophetesses. At the brothers' instruction, the soothsayers announced "in their ravings" that God had consented to the uprising against the Byzantines, and Saint Demetrius would abandon Thessaloniki and "come over to them to be their helper and assistant" during the forthcoming rebellion. This "professional work of manipulation" was effective: all who were present willingly joined the brothers' movement. Niketas Choniates, who recorded these events, did not name the venue of the gathering, but Tarnovo is the most probable place according to modern scholars' views. Taking advantage of the war between the Byzantine Empire and the Normans of Sicily, the rebels invaded Thrace and persuaded others to join them. Heartened by the victories, Theodor-Peter "bound his head with a gold chaplet and fashioned scarlet buskins to put on his feet", thus adopting insignia that had been used only by the emperors. Although Choniates does not mention that Theodor-Peter also styled himself emperor, the use of imperial insignia shows that he either had been proclaimed emperor, or at least laid claim to the title. Madgearu says, the coronation most probably took place before the end of 1185, because a priest, Basil, was allegedly made the head of the restored Bulgarian Orthodox Church in that year.