Workers seal the doors to the conclave in Rome on Feb. 27, 1939, as the cardinals meet to elect a successor to Pope Pius XI.
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With all 62 living cardinals in attendance, the conclave to elect a successor to Pope Pius XI began on March 1, 1939, and ended a day later after three ballots. The cardinals elected Eugenio Cardinal Pacelli who took the name of Pius XII.
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Cardinals of the Roman Catholic Church meet at the Vatican on Oct. 10, 1958, to name Msgr. Federico Callori De Vignale to be governor of the conclave to elect a successor to Pope Pius XII.
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The 1963 conclave at the Sistine Chapel in Vatican City was the largest ever assembled at that time, with 80 cardinals attending.
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A look inside the room prepared for Jossef Cardinal Mindasenty, Primate of Hungary, in the Vatican conclave area on June 15, 1963. His cell was one of the most luxurious of the 82 cells prepared for the conclave held to elect a successor to Pope John XXIII.
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Thick puffs of white smoke pour out from a smokestack over the Sistine Chapel of the Vatican Palace on June 21, 1963, announcing that the Roman Catholic Cardinals assembled in conclave have elected the successor of Pope John XXIII.
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The Papal conclave of October 1978 was triggered by the sudden death of Pope John Paul I after only 33 days in office. When the cardinals elected John Paul I on Aug. 26, 1978, they expected he would reign for at least a decade. Instead they found themselves having to elect his successor within six weeks.
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Italian Cardinal Giacomo Biffi takes an oath at the beginning of the conclave to elect the next pope in the Sistine Chapel at the Vatican on April 18, 2005.
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Cardinal Joseph Ratzinger of Germany was elected pope April 19, 2005, in the first Roman Catholic conclave of the new millennium. He chose the name Pope Benedict XVI.
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Cardinals attend the Pro Eligendo Romano Pontifice Mass at St. Peter's Basilica before they enter the conclave on March 12, 2013, to vote for a successor to Pope Benedict XVI after he became the first pope in 600 years to resign.