After being occupied with suppressing the revolt of Bardas Phokas throughout the year 970, Tzimiskes marshalled his forces in early 971 for a campaign against the Rus', moving his troops from Asia to Thrace and gathering supplies and siege equipment. The Byzantine navy accompanied the expedition, tasked with carrying troops to effect a landing in the enemy's rear and to cut off their retreat across the Danube. The emperor chose Easter week of 971 to make his move, catching the Rus' completely by surprise: The passes of the Balkan mountains had been left unguarded, either because the Rus' were busy suppressing Bulgarian revolts or perhaps (as A.D. Stokes suggests) because a peace agreement that had been concluded after the battle of Arcadiopolis made them complacent.

The Byzantine army, led by Tzimiskes in person and numbering 30,000–40,000, advanced quickly and reached Preslav unmolested. The Rus' army was defeated in a battle before the city walls, and the Byzantines proceeded to lay siege. The Rus' and Bulgarian garrison under the Rus' noble Sphangelput up a determined resistance, but the city was stormed on 13 April. Among the captives were Boris II and his family, who were brought to Constantinople along with the Bulgarian imperial regalia. The main Rus' force under Sviatoslav withdrew before the imperial army towards Dorostolon on the Danube. As Sviatoslav feared a Bulgarian uprising, he had 300 Bulgarian nobles executed, and imprisoned many others. The imperial army advanced without hindrance; the Bulgarian garrisons of the various forts and strongholds along the way surrendered peacefully.