Sviatoslav's invasion of Bulgaria

Sviatoslav's invasion of Bulgaria
Part of the Rus'–Byzantine Wars and Byzantine–Bulgarian Wars
Sviatoslav's invasion, from the Manasses Chronicle.
Date 967/968–971 Location Moesia and Thrace Result Sviatoslav victory against Bulgaria [1] Byzantine victory over Kievan Rus’ Start of the Byzantine conquest of Bulgaria
Belligerents
Kievan Rus', Pechenegs, Magyars	Bulgaria	Byzantine Empire
Commanders and leaders
Sviatoslav I of Kiev Sphangel †(?) Ikmor †	Peter I of Bulgaria Boris II of Bulgaria	John I Tzimiskes Bardas Skleros
Strength
60,000+ men	~30,000 men	~30–40,000 men

Sviatoslav's invasion of Bulgaria refers to a conflict beginning in 967/968 and ending in 971, carried out in the eastern Balkans, and involving the Kievan Rus', Bulgaria, and the Byzantine Empire. The Byzantines encouraged the Rus' ruler Sviatoslav to attack Bulgaria, leading to the defeat of the Bulgarian forces and the occupation of the northern and north-eastern part of the country by the Rus' for the following two years. The allies then turned against each other, and the ensuing military confrontation ended with a Byzantine victory. The Rus' withdrew and eastern Bulgaria was incorporated into the Byzantine Empire.

In 927, a peace treaty had been signed between Bulgaria and Byzantium, ending many years of warfare and establishing forty years of peace. Both states prospered during this interlude, but the balance of power gradually shifted in favour of the Byzantines, who made great territorial gains against the Abbasid Caliphate in the East and formed a web of alliances surrounding Bulgaria. By 965/966, the warlike new Byzantine emperor Nikephoros II Phokas refused to renew the annual tribute that was part of the peace agreement and declared war on Bulgaria. Preoccupied with his campaigns in the East, Nikephoros resolved to fight the war by proxy and invited the Rus' ruler Sviatoslav to invade Bulgaria.

Sviatoslav's subsequent campaign greatly exceeded the expectations of the Byzantines, who had regarded him only as a means to exert diplomatic pressure on the Bulgarians. The Rus' prince conquered the core regions of the Bulgarian state in the northeastern Balkans in 967–969, seized the Bulgarian tsar Boris II, and effectively ruled the country through him. Sviatoslav intended to continue his drive south against Byzantium itself, which in turn regarded the establishment of a new and powerful Russo-Bulgarian state in the Balkans with great concern. After stopping a Rus' advance through Thrace at the Battle of Arcadiopolis in 970, the Byzantine emperor John I Tzimiskes led an army north into Bulgaria in 971 and captured Preslav, the capital. After a three-month siege of the fortress of Dorostolon, Sviatoslav agreed to terms with the Byzantines and withdrew from Bulgaria. Tzimiskes formally annexed Eastern Bulgaria to the Byzantine Empire. However, most of the country in the central and western Balkans remained in effect outside imperial control; this would lead to the revival of the Bulgarian state in these regions under the Cometopuli dynasty.