Why Famous: The 262nd Pope. Reigned from 1958-1963. Called the historic Second Vatican Council.
- 1904-08-10 Angelo Giuseppe Roncalli (future Pope John XXIII) becomes a priest
- 1925-03-19 Angelo Giuseppe Roncalli (future Pope John XXIII) becomes a bishop, appointed as Apostolic Visitor to Bulgaria
- 1958-10-28 Angelo Giuseppe Roncalli elected Pope, taking name John XXIII
- 1958-11-04 Angelo Giuseppe Roncalli crowned as pope John XXIII
- 1959-01-25 Pope John XXIII proclaims 2nd Vatican council
- 1959-06-29 Pope John XXIII 1st encyclical "On truth, unity, & peace, in charity"
- 1959-08-01 Pope John XXIII publishes encyclical Sacerdotii nostri primordia
- 1959-11-28 Pope John XXIII publishes encyclical Princeps Pastorum
- 1961-05-15 Pope John XXIII publishes encyclical Mater et Magistra
- 1962-01-03 Pope John XXIII excommunicates Fidel Castro
- 1962-10-11 Second Vatican Council (21st ecumenical) convened by Pope John XXIII
- 1963-04-11 John XXIII encyclical On peace in truth, justice, charity & liberty