Video: 'Pope John XXIII Tribute - 1963 | Today in History | 3 June 16'

(Monday, June 3, 1963, 7:49 p.m. Central European Time) — Pope John XXIII, champion of world peace and a tireless fighter for the union of all Christian churches, died in the Vatican tonight while Cardinals and other prelates and several of his relatives prayed around his sickbed.

The Pope, 81, suffered from stomach cancer, complicated by peritonitis, ending a relatively brief but highly influential 4 1/2-year papacy.

Video: 'World Mourns Pope John (1963)'

Born Angelo Giuseppe Roncalli, he was unexpectedly elected pope on Oct. 28, 1958, at age 76 after eleven ballots. Pope John XXIII surprised those who expected him to be a caretaker pope by calling the historic Second Vatican Council (1962–1965), the first session opening on Oct. 11, 1962.

Pope John XXIII called the council because he felt the Church needed “updating” (in Italian: aggiornamento). In order to connect with 20th-century people in an increasingly secularized world, some of the Church’s practices needed to be improved and its teaching needed to be presented in a way that would appear relevant and understandable to them.

Video: 'John XXIII, the surprising pope'

Many Council participants were sympathetic to this, while others saw little need for change and resisted efforts in that direction.

Video: 'The Fabulous Sixties: 1963' (Pope John XXIII dead at 24:27)

Support for aggiornamento won out over resistance to change, and as a result, the sixteen magisterial documents produced by the council proposed significant developments in doctrine and practice: an extensive reform of the liturgy, a renewed theology of the Church, of revelation and of the laity, and new approaches to relations between the Church and the world, to ecumenism, to non-Christian religions, and to religious freedom.

He would be succeeded by Pope Paul VI.