Saint Vladimir Svyatoslavich the Great (c. 958–1015) was the grand prince of Kiev who converted to Christianity in 988, and proceeded to baptise the whole Kievan Rus. His name may be spelled in different ways: in Old East Slavic as Volodimir, in modern Ukrainian as Volodymyr, in Old Church Slavonic and modern Russian as Vladimir, and in the Norse and modern Scandinavian languages as Valdemar.

Vladimir was the youngest son of Svyatoslav I by his housekeeper Malusha, described in the Norse sagas as a prophetess who lived to the age of 100 and was brought from her cave to the palace to predict the future. Hagiographic tradition of dubious authenticity connects his childhood with the name of his grandmother, Olga Prekrasa, who was Christian and governed the capital during Svyatoslav's frequent military campaigns.

Transferring his capital to Pereyaslavets in 969, Sviatoslav designated Vladimir ruler of Novgorod the Great but gave Kiev to his legitimate son Yaropolk. After Sviatoslav's death (972), a fratricidal war erupted (976) between Yaropolk and his younger brother Oleg, ruler of the Drevlians. In 977 Vladimir fled to his kinsmen in Scandinavia, collecting as many of the Viking warriors as he could to assist him to recover Novgorod, and on his return the next year marched against Yaropolk.

On his way to Kiev he sent ambassadors to Rogvolod (Norse: Ragnvald), prince of Polotsk, to sue for the hand of his daughter Rogneda (Norse: Ragnhild). The well-born princess refused to affiance herself to the son of a bondswoman, but Vladimir attacked Polotsk, slew Rogvolod, and took Ragnhild by force. Actually, Polotsk was a key fortress on the way to Kiev, and the capture of Polotsk and Smolensk facilitated the taking of Kiev (980), where he slew Yaropolk by treachery, and was proclaimed konung, or kagan, of all Kievan Rus.

Years of pagan rule
In addition to his father's extensive domain, Vladimir continued to expand his territories. In 981 he conquered the Cherven cities, the modern Halychyna; in 983 he subdued the Yatvyags, whose territories lay between Lithuania and Poland; in 985 he led a fleet along the central rivers of Russia to conquer the Bulgarians of the Kama, planting numerous fortresses and colonies on his way.

Though Christianity had won many converts since Olga's rule, Vladimir had remained a thorough going pagan, taking eight hundred concubines (besides numerous wives) and erecting pagan statues and shrines to gods. It is argued that he attempted to reform Slavic paganism by establishing the thunder-god Perun as a supreme deity. It is probable that he instituted the practice of human sacrifices as well.

Baptism of Rus
In the year 987, as the result of a consultation with his boyars, Vladimir sent envoys to study the religions of the various neighboring nations whose representatives had been urging him to embrace their respective faiths. The result is amusingly described by the chronicler Nestor. Of the Muslim Bulgarians of the Volga the envoys reported there is no gladness among them; only sorrow and a great stench, and that their religion was undesirable due to its taboo against alcoholic beverages and pork. Russian sources also describe Vladimir consulting with Jewish envoys (who may or may not have been Khazars), and questioning them about their religion but ultimately rejecting it, saying that their loss of Jerusalem was evidence of their having been abandoned by God. Ultimately Vladimir settled on Christianity. In the churches of the Germans his emissaries saw no beauty; but at Constantinople, where the full festival ritual of the Byzantine Church was set in motion to impress them, they found their ideal: "We no longer knew whether we were in heaven or on earth," they reported, "nor such beauty, and we know not how to tell of it." If Vladimir was impressed by this account of his envoys, he was yet more so by political gains of the Byzantine alliance.

In 988, having taken the town of Chersones in Crimea, he negotiated for the hand of the emperor Basil II's sister, Anna. Never had a Greek princess married a Barbarian before, as matrimonial offers of French kings and German emperors had been peremptorily rejected. In short, to marry the 27-year-old princess to a pagan Slav seemed impossible. Vladimir, however, was baptized at Chersones, taking the Christian name of Basil out of compliment to his imperial brother-in-law; the sacrament was followed by his marriage with the Roman princess. Returning to Kiev in triumph, he destroyed pagan monuments and established many churches, starting with the splendid Church of the Tithes (989) and monasteries on Mt. Athos.

Christian reign
He now formed a great council out of his boyars, and set his twelve sons over his subject principalities. With his neighbors he lived at peace, the incursions of the savage Pechenegs alone disturbing his tranquillity. After Anna's death, he married again, most likely to a granddaughter of Otto the Great.

He died at Berestovo, near Kiev, while on his way to chastise the insolence of his son, Prince Yaroslav of Novgorod. The various parts of his dismembered body were distributed among his numerous sacred foundations and were venerated as relics. One of the largest Kievan cathedrals is dedicated to him. The University of Kiev was named after the man who both civilized and Christianized Kievan Rus. There is the Order of St. Vladimir in Russia. The Roman Catholic and Eastern Orthodox churches celebrate the feast day of St. Vladimir on 15 July.

His memory was also kept alive by innumerable folk ballads and legends, which refer to him as Krasno Solnyshko, that is, the Fair Sun. With him the Varangian period of Eastern Slavic history ceases and the Christian period begins.