Pope Paul VI was head of the Catholic Church and sovereign of the Vatican City State from 21 June 1963 to his death in 1978. Succeeding John XXIII, he continued the Second Vatican Council, which he closed in 1965, implementing its numerous reforms. He fostered improved ecumenical relations with Eastern Orthodox and Protestant churches, which resulted in many historic meetings and agreements.
Montini served in the Holy See's Secretariat of State from 1922 to 1954. While in the Secretariat of State, Montini and Domenico Tardini were considered to be the closest and most influential advisors of Pope Pius XII. In 1954, Pius named Montini Archbishop of Milan, the largest Italian diocese. Montini later became the Secretary of the Italian Bishops' Conference. John XXIII elevated him to the College of Cardinals in 1958, and after the death of John XXIII, Montini was considered one of his most likely successors. Upon his election to the papacy, Montini took the name Paul VI.
He re-convened the Second Vatican Council, which had automatically closed with the death of John XXIII.