Gregory XII

Gregory XII resigned so that a special council in Constance, which is in modern-day Germany, could excommunicate the Avignon-based pope and start again with a new, single leader of the Catholic Church.

Pope Benedict's resignation will be the first voluntary departure from the seat since Pope Gregory XII resigned in 1415.

The last pope to resign was Pope Gregory XII, who stepped down in 1415.

Another pope, Gregory XII reluctantly abdicated in 1415 to end a dispute with a rival claimant to the papacy.

This decision was especially shocking, since he is the first pope to resign from the papacy since Gregory XII in 1415 and the first to do so voluntarily since Celestine V in 1294.

Pope Gregory XII was pontiff between 1406 and 1415 and reigned at a time where the papacy was split with illegitimate pontiffs in Avignon and Pisa claiming to be the true heir to the Holy See.

Pope Benedict XVI (right) yesterday became the first Pope to resign since Gregory XII almost 600 years ago, illustrating that having Roman numerals after your name is never a good idea.

Pope Gregory XII quit in 1415 to end the Western Schism, which saw three claimants vying for the papacy.

They are: Pontian in 235; Silverius in 537; John XVIII in 1009; Benedict IX in 1045; Celestine V in 1294 and Gregory XII in 1415.

Then, Pope Gregory XII stepped down to end what was known as the Great Western Schism between competing papal claimants.

The Pisan allegiance replaced him with Cossa, but there were now three popes in contention: Cossa as John XXIII, Gregory XII in Rome and Benedict XIII in Avignon.

(100) The history of the Renaissance papacy is full of instances of popes scheming to have their relatives succeed them, which, in fact, many eventually did: Eugenius IV (1431-47) succeeded his uncle Gregory XII (1406-15) and Eugenius' nephew Paul II (1464-71) followed him.

Pope Gregory XII later changed the feast to Our Lady of the Rosary.

Pope Gregory XII, whose name is given to the Gregorian calendar

Third, there have been precedents of such resignation, for instance, of Gregory XII in 1415, the first to have done so voluntarily since Celestine V in 1294.