Pope Gregory XII - who reigned from 1406 to 1415 - did so to end what was called the Western Schism.

BBC: How does a Pope resign from office?

Yet many Jews believe that the Vatican has not gone far enough and are furious at Vatican efforts to make the war-time pope, Pius XII, a saint.

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There were three rival claimants to the papal throne at that time - the Roman Pope Gregory XII, the Avignon Pope Benedict XIII, and the Antipope John XXIII.

BBC: How does a Pope resign from office?

But the Vatican does not accept Pius XII was culpable of assenting to the Holocaust, and - even if it did - it would be impossible to cast blame on a pope whom the current pope has begun moves to beatify.

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The museum includes controversial wording that reflects a long-running dispute over the role of Pope Pius XII during World War II.

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