At the end of the 10th century, Dobruja was the theatre of operations between the Kievan Rus army led by Prince Sviatoslav I, the Bulgarian army and the Byzantine army led by emperor John Tzimiskes. Sviatoslav controlled large parts of the First Bulgarian Empire and established his capital at Pereyaslavets (near modern Nufăru) on the Danube. The Byzantines, led by John Tzimiskes were on the offensive after they defeated the united Russo-Bulgarian forces in the Battle of Arcadiopolis. Pereyaslavets was captured and Sviatoslav was forced to flee westwards to the fortress of Dorostolon (Durostorum). Emperor John proceeded to lay siege to Dorostolon, which resisted for sixty five days until Sviatoslav agreed to sign a peace treaty with the Byzantine Empire, whereby he renounced his claims on Bulgaria and the city of Chersonesos in Crimea. Sviatoslav was allowed to evacuate his army to Kiev.