In 1268, the Church was facing a sede vacante(a vacant see) and the election of a new Pope. At that point, 19 of the 20 cardinal electors traveled to Viterbo to take part in choosing a successor. Little did anyone know, this election would become the longest conclave in Church history.

After a year without a new Pope being chosen, the citizens of Viterbo took matters into their own hands. In an attempt to pressure the cardinals to make a decision, they, together with the captain of the people, Raniero Gatti, locked the cardinals in the Palace of the Popes with a key or “cum clave”, in Latin from which the word conclave is derived. The cardinals, locked in from the outside, were also limited to bread and water.

Finally, in September of 1271, after more than three years without a pontiff, Pope Gregory X was elected.

Lessons learned

Following the experience in Viterbo, some of the cardinals realized that the long and unofficial process of electing Popes was outdated. The recently elected pontiff, Gregory X, published an Apostolic Constitution, Ubi periculum, with concrete rules for the selection of a new Pope. This apostolic constitution remains the basis for the modern-day process the Church still uses today.