Kaloyan decided to take vengeance of the townspeople of Philippopolis, who had voluntarily cooperated with the crusaders. With the assistance of the local Paulicians, he seized the town and ordered the murder of the most prominent burghers. The commoners were delivered in chains to Vlachia (a loosely defined territory, located to the south of the lower Danube). He returned to Tarnovo after a riot had broken out against him in the second half of 1205 or early 1206. He "subjected the rebels to harsh punishments and novel methods of execution", according to Choniates. He again invaded Thrace in January 1206. He captured Rousion (now Keşan in Turkey) and massacred its Latin garrison. He then destroyed most of the fortresses along the Via Egnatia, as far as Athira (present-day Büyükçekmece in Turkey). The local inhabitants were captured and forcibly relocated to the lower Danube. Akropolites recorded that thereafter Kaloyan called himself "Romanslayer", with a clear reference to Basil II who had been known as the "Bulgarslayer" after his destruction of the First Bulgarian Empire.