By virtue of their position of world importance, many popes are persons of fame. Among those who greatly increased the secular power of the papacy were St. Gregory I (the Great, 540?–604), pope from 590 to 604, who also was influential in matters of doctrine, liturgy, and missionary work; St. Gregory VII (Hildebrand, 1020?–1085), pope from 1073 to 1085, who engaged in conflict with Holy Roman Emperor Henry IV, forcing him to do public penance at the village of Canossa, and later was driven from Rome by him; and Alexander VI (Rodrigo Lanzol y Borja, b. Spain, 1431?–1503), pope from 1492 to 1503, who also divided colonial territories in the New World between Spain and Portugal.
The most significant 19th-century pope was Pius IX (Giovanni Maria Mastai-Ferretti, 1792–1878), pope from 1846 to 1878, who lost the Papal States to the kingdom of Italy and convened the First Vatican Council (1869–70), which established the doctrine of papal infallibility in matters of faith and morals. The first popes who reigned since the establishment of the Vatican City State in 1929 were Pius XI (Achille Damiano Ratti, 1857–1939), from 1922 to 1939, and Pius XII (Eugenio Pacelli, 1876–1958), from 1939 to 1958. John XXIII (Angelo Giuseppe Roncalli, 1881–1963), pope from 1958 to 1963, made history by convening the Second Vatican Council (1962–65), by altering the text of the canon of the mass for the first time since the 7th century, and by strongly defining the position of the Church on problems of labor and social progress (in his encyclical Mater et Magistra of June 1961). His greatest achievement was generally considered to be his eighth encyclical, Pacem in Terris (issued on 10 April 1963), a profound plea for peace, in which he hailed the UN as a defender of human rights.
Paul VI (Giovanni Battista Montini, 1897–1978), pope from 1963 to 1978, continued Pope John's effort to attain unity of the Christian world. On 4 October 1965, he addressed the UN General Assembly, appealing for world peace and international cooperation. He presided over the concluding sessions of the Second Vatican Council and traveled to many places, including the Holy Land.
Albino Luciani (1912–78), patriarch of Venice, was elected pope on 26 August 1978 and took the name John Paul I. He died on 28 September after a reign of only 34 days. His successor, John Paul II (Karol Wojtyla, b.1920), was elevated to the papacy on 16 October 1978. This former archbishop of Cracow was not only the first Polish pope but also the first non-Italian pope since the Renaissance. Despite suffering severe wounds in a 1981 assassination attempt, John Paul II has continued to travel widely. To the dismay of Jewish and other leaders, John Paul II granted Austrian President Kurt Waldheim (b.1918) an audience in June 1987, despite accusations that Waldheim had taken part in war crimes during World War II when he was an officer in the German army.