Vitalian was born in Segni, Campagna (Italy), the son of Anastasius. He entered the priesthood and was active in the Church of Rome, being consecrated bishop to replace Pope St. Eugene I on July 30, 657. Vitalian continued the Roman Church's battle against Monothelitism that had so occupied his immediate predecessors. He was on better terms than they with Byzantine emperor Constans II, and after Constans was assassinated in 688, supported his son, Constantine IV, in his political struggles. However, he was unable to get Byzantium to abrogate the heresy. He was more successful in promoting Catholicism in the West. In 664, at the Synod of Streaneshalch (Whitby), King Oswy of Northumberland decided to observe Easter according to the Roman Church and to follow it in the shape of the tonsure. He dispatched a candidate for archbishop to be consecrated by the pope, but the man died in Rome. Vitalian then decided to send St. Theodore of Tarsus in his stead. Theodore was consecrated by Vitalian on March 26, 688, and went to England, where he was recognized as archbishop of Canterbury and head of the Church in England by all the clergy. Vitalian died on January 27, 672, and was buried in St. Peter's at the Vatican.