Date of birth unknown; died 972 or 973. Grand Prince of Kiev (c. 945–72); military commander.
Under Sviatoslav Igorevich, the Kievan state was ruled until 969 largely by his mother, Princess Ol’ga, since Sviatoslav himself was almost perpetually on military campaigns. In the period 964–966 he liberated the Viatichi from the Khazars and brought them under the rule of Kiev. In the 960’s he defeated the Khazar Khaganate and destroyed the Khazar cities of Sarkel (on the Don) and Itil’, the khaganate’s capital. He warred against the Volga-Kama Bulgars and captured their capital on the Volga. In the Northern Caucasus he took the Khazar fortress of Semender and defeated the Iasy (Alani) and Kasogi (Adygs).
In 967 or 968, at the suggestion of Byzantium, which was attempting to set its neighbors Rus’ and Bulgaria against each other and thus to weaken both, Sviatoslav Igorevich invaded Bulgaria, establishing his headquarters at Pereiaslavets, at the mouth of the Danube. The Byzantine government, in order to prevent Sviatoslav from entrenching himself in Bulgaria, unleashed the Pechenegs on Kiev. Sviatoslav Igorevich returned to defend his capital; after repulsing the Pechenegs, however, he returned to Bulgaria. In about 971 he allied himself with the Bulgars and Magyars and resumed the conflict against Byzantium. In 971, after engaging numerically superior Byzantine forces near Bol’shoi Preslav and Dorostolum (now Silistra) and withstanding a siege of three months, he concluded a peace with the Byzantine emperor John I Tzimisces. On the return trip to Kiev, Sviatoslav Igorevich died at the Dnieper rapids while fighting the Pechenegs, whom Byzantium had forewarned of Svjatoslav’s return.