1881: Born Angelo Giuseppe Roncalli on Nov. 25. He is the fourth in a family of 13 children to Giovanni Battista and Marianna Giulia Roncalli, a family of sharecroppers in Sotto il Monte, Italy.
1892: Enters the seminary at Bergamo.
1901: Leaves Rome, where he is studying; takes a year off for military service.
1904: Ordained a priest on Aug.10, serves as secretary to the bishop of Bergamo.
1905: Begins teaching classes on history, as well as the lives and teachings of the church fathers, at Bergamo seminary.
1915: Returns to military service, serving as medic and chaplain during World War I.
1918: In Bergamo, he opens a student hostel.
1921: He is called to Rome as the head of the Italian national office of the Society for the Propagation of the Faith.
1925: Named archbishop and appointed apostolic visitator to Bulgaria, working closely with Eastern Catholics.
1934: Transfers to Istanbul, where he serves as apostolic delegate to Turkey and Greece, improving relations with the Orthodox and Muslims.
1939-44: During World War II, he helps many Jews escape Nazi persecution by issuing "transit visas" and coordinating rescue plans with other ambassadors.
1944: Becomes nuncio to Paris.
1953: Named a cardinal and patriarch of Venice.
1958: Called to Rome for a conclave; is elected Oct. 28 and takes the name John XXIII. At age 76, he is the oldest pope to be elected in more than 200 years.
1961: Issues "Mater et Magistra" ("Mother and Teacher"), an encyclical on social issues that emphasizes the obligations of nations and individuals to bring about social justice.
1962: Opens the first session of the Second Vatican Council on Oct. 11, setting in motion major reforms of the church.
1963: At the height of the Cold War, he releases his second social encyclical, "Pacem in Terris" ("Peace on Earth"), teaching that true peace must be built on the pillars of truth, justice, love and freedom.
1963: Dies of cancer on June 3.
Source: Catholic News Service