In 917, a Byzantine army led by Leo Phokas the Younger invaded Bulgaria, but was decisively defeated at the Battle of Achelous on 20 August 917. After Achelous, Symeon sent an army led by Pavle (the son of Bran), to take the Serbian throne, but failed, as Petar proved a good opponent. Symeon sent generals, Marmaim and Theodore Sigritzes, persuading Petar (through an oath) to come out and meet them, then captured and took him to Bulgaria where he was put in prison, dying within a year. His remains are entombed in the Church of the Holy Apostles Peter and Paul in Stari Ras, the capital. Symeon put Pavle on the Serbian throne.