stylistic:tone
Campaigns in the Balkans

The annihilation of Khazaria was undertaken against the background of the Rus'-Byzantine alliance, concluded in the wake of Igor's Byzantine campaign in 944. Close military ties between the Rus' and Byzantium are illustrated by the fact, reported by John Skylitzes, that a Rus' detachment accompanied Byzantine Emperor Nikephoros Phokas in his victorious naval expedition to Crete.

In 967 or 968, Nikephoros sent his agent, Kalokyros, to persuade Sviatoslav to assist the Byzantines in a war against Bulgaria. Sviatoslav was paid 15,000 pounds of gold and set sail with an army of 60,000 men, including thousands of Pecheneg mercenaries.

Sviatoslav defeated the Bulgarian ruler Boris II and proceeded to occupy the whole of northern Bulgaria. Meanwhile, the Byzantines bribed the Pechenegs to attack and besiege Kiev, where Olga stayed with Sviatoslav's son Vladimir. The siege was relieved by the druzhina of Pretich, and immediately following the Pecheneg retreat, Olga sent a reproachful letter to Sviatoslav. He promptly returned and defeated the Pechenegs, who continued to threaten Kiev.

Sviatoslav refused to turn his Balkan conquests over to the Byzantines, and the parties fell out as a result. To the chagrin of his boyars and his mother (who died within three days after learning about his decision), Sviatoslav decided to move his capital to Pereyaslavets in the mouth of the Danube due to the great potential of that location as a commercial hub. In the Primary Chronicle record for 969, Sviatoslav explains that it is to Pereyaslavets, the centre of his lands, "all the riches flow: gold, silks, wine, and various fruits from Greece, silver and horses from Hungary and Bohemia, and from Rus' furs, wax, honey, and slaves".

In summer 969, Sviatoslav left Rus' again, dividing his dominion into three parts, each under a nominal rule of one of his sons. At the head of an army that included Pecheneg and Magyar auxiliary troops, he invaded Bulgaria again, devastating Thrace, capturing the city of Philippopolis, and massacring its inhabitants. Nikephoros responded by repairing the defenses of Constantinople and raising new squadrons of armored cavalry. In the midst of his preparations, Nikephoros was overthrown and killed by John Tzimiskes, who thus became the new Byzantine emperor.

John Tzimiskes first attempted to persuade Sviatoslav to leave Bulgaria, but he was unsuccessful. Challenging Byzantine authority, Sviatoslav crossed the Danube and laid siege to Adrianople, causing panic in the streets of Constantinople in summer 970. Later that year, the Byzantines launched a counteroffensive. Being occupied with suppressing a revolt brought by Bardas Phokas in Asia Minor, John Tzimiskes sent his commander-in-chief, Bardas Skleros, who defeated the coalition of Rus', Pechenegs, Magyars, and Bulgarians in the Battle of Arcadiopolis. Meanwhile, John, having quelled the revolt of Bardas Phokas, came to the Balkans with a large army and promoting himself as the liberator of Bulgaria from Sviatoslav, penetrated the impracticable mountain passes and shortly thereafter captured Marcianopolis, where the Rus' were holding a number of Bulgar princes hostage.

Sviatoslav retreated to Dorostolon, which the Byzantine armies besieged for sixty-five days. Cut off and surrounded, Sviatoslav came to terms with John and agreed to abandon the Balkans, renounce his claims to the southern Crimea, and return west of the Dnieper River. In return, the Byzantine emperor supplied the Rus' with food and safe passage home. Sviatoslav and his men set sail and landed on Berezan Island at the mouth of the Dnieper, where they made camp for the winter. Several months later, according to the Primary Chronicle, their camp was devastated by famine, so that even a horse's head could not be bought for less than a half- grivna. While Sviatoslav's campaign brought no tangible results for the Rus', it weakened the Bulgarian state and left it vulnerable to the attacks of Basil the Bulgar-Slayer four decades later.