After the Byzantines defeated the united Rus'-Bulgarian forces in the Battle of Arcadiopolis and recaptured Pereyaslavets, Svyatoslav was forced to flee to the northern fortress of Dorostolon (Drustur/Dorostorum). Emperor John proceeded to lay siege to Dorostolon, which lasted for 65 days. His army was reinforced by a fleet of 300 ships equipped with Greek fire. The Rus' felt they could not break the siege and agreed to sign a peace treaty with the Byzantine Empire, whereby they renounced their interests towards the Bulgarian lands and the city of Chersonesos in Crimea.