Vladimir I (vlăd´əmĬr´, Rus. vlədyē´mĬr), Volodymyr I (vŭl´ədyē´myĬr), or Saint Vladimir, d. 1015, first Christian grand duke of Kiev (c.980–1015); son of Sviatoslav. In 970, Vladimir was sent by his father to govern Novgorod. After Sviatoslav's death Vladimir vied with his two brothers, Yaropolk and Oleg, for the succession. About 980, he defeated his brothers and became grand duke of Kiev. During his reign he conquered and united under Kievan Rus distant Slavic tribes and waged successful wars on the Lithuanians, the Bulgars, and the Byzantines in Crimea. At first a fervent pagan, he converted to Christianity, probably influenced by the political and economic advantages of an alliance with Byzantium. His baptism, in 988 or 989, was followed by his marriage to Anna, sister of the Byzantine Emperor Basil II. After the wedding he returned Kherson (in Crimea) to Byzantium. Vladimir renounced his profligate ways and made Greek Orthodox Christianity the religion of his people. He devoted the remainder of his life to the building of churches, including the splendid Cathedral of the Tithes (989), and to the establishment of schools and libraries. He also enacted several statutes concerning the legal status and courts of the church. Feast: July 15.