Vladimir I of Kiev in the context of "Sviatoslav I"

The Varangian Guard (Greek: Τάγμα τῶν Βαράγγων, romanized: Tágma tōn Varángōn) was an elite unit of the Byzantine army from the 10th to the 14th century who served as personal bodyguards to the Byzantine emperors. The Varangian Guard was known for being primarily composed of recruits from Northern Europe, including mainly Norsemen from Scandinavia but also Anglo-Saxons from England. The recruitment of distant fighters from outside Byzantium to serve as the emperor's personal guard was pursued as a deliberate policy, as they lacked local political loyalties and could be counted upon to suppress revolts by disloyal Byzantine factions.

The Rus' provided the earliest members of the Varangian Guard. They were in Byzantine service from as early as 874. The Guard was first formally constituted under Emperor Basil II in 988, following the Christianization of Kievan Rus' by Vladimir I of Kiev. Vladimir, who had recently taken control of Kiev with an army of Varangian warriors, sent 6,000 men to Basil as part of a military assistance agreement. Basil's distrust of the native Byzantine guardsmen, whose loyalties often shifted with fatal consequences, as well as the proven loyalty of the Varangians, many of whom had previously served in Byzantium, led the Emperor to employ them as his personal guardsmen.