As a result of the length of the election, during which three of the twenty cardinal-electors died and one resigned, Gregory X promulgated the apostolic constitution, Ubi periculum, on July 7, 1274 (or 16), during the Second Council of Lyon, establishing the papal conclave, whose rules were based on the tactics employed against the cardinals in Viterbo. The election itself is sometimes viewed as the first conclave.
Some sources say there were only nineteen cardinal electors; others eighteen or seventeen. In any event, after August 11, 1270, there were only sixteen remaining cardinal electors.
| Elector | Nationality | Order | Title | Elevated | Elevator | Notes |
|---|---|---|---|---|---|---|
| Odo of Châteauroux, O.Cist. | French | Cardinal-bishop | Bishop of Frascati | 1244, May 28 | Innocent IV | Dean of the Sacred College of Cardinals; Camerlengo of the Holy Roman Church |
| Stefan Vancza† | Hungarian | Cardinal-bishop | Bishop of Palestrina | 1251, December | Innocent IV | Died on July 9, 1270, first Hungarian cardinal |
| John of Toledo, O.Cist. | English | Cardinal-bishop | Bishop of Porto e Santa Rufina | 1244, May 28 | Innocent IV | |
| Henry of Segusio | French | Cardinal-bishop | Bishop of Ostia and Velletri | 1262, May 22 | Urban IV | Resigned and departed on June 8, 1270 |
| Simone Paltineri (or Paltinieri) | Paduan | Cardinal-priest | Titulus Ss. Silvestro e Martino ai Monti | 1261, December 17 | Urban IV | Committee member; Cardinal primoprete |
| Simon Monpitie de Brie | French | Cardinal-priest | Titulus S. Cecilia | 1261, December 17 | Urban IV | Future Pope Martin IV |
| Anchero Pantaleone | French | Cardinal-priest | Titulus S. Prassede | 1262, May 22 | Urban IV | Cardinal-nephew |
| Guillaume de Bray | French | Cardinal-priest | Titulus S. Marco | 1262, May 22 | Urban IV | Camerlengo of the Sacred College of Cardinals |
| Guy de Bourgogne (or Guido), O.Cist. | French | Cardinal-priest | Titulus S. Lorenzo in Lucina | 1262, May 22 | Urban IV | Committee member |
| Annibale Annibaldeschi de Molaria, O.P. | Roman | Cardinal-priest | Titulus Ss. XII Apostoli | 1262, May 22 | Urban IV | Treated with Philip III of France and Charles I of Naples |
| Riccardo Annibaldeschi di Molaria, O.S.B. | Roman | Cardinal-deacon | Deacon of S. Angelo in Pescheria | 1237 | Gregory IX | Committee member Nephew of Pope Alexander IV; Protodeacon |
| Ottaviano Ubaldini | Florentine | Cardinal-deacon | Deacon of S. Maria in Via Lata | 1244, May 28 | Innocent IV | Committee member |
| Giovanni Gaetano Orsini | Roman | Cardinal-deacon | Deacon of S. Nicola in Carcere | 1244, May 28 | Innocent IV | Committee member Future Pope Nicholas III |
| Ottobono Fieschi dei Conti di Lavagna | Genoese | Cardinal-deacon | Deacon of S. Adriano | 1251, December | Innocent IV | Future Pope Adrian V, Cardinal-nephew |
| Uberto Coconati dei Conti d'Elci | Sienese | Cardinal-deacon | Deacon of S. Eustachio | 1261, December 17 | Urban IV | |
| Giacomo Savelli | Roman | Cardinal-deacon | Deacon of S. Maria in Cosmedin | 1261, December 17 | Urban IV | Committee member Future Pope Honorius IV |
| Goffredo (Geoffroy) da Alatri | Neapolitan | Cardinal-deacon | Deacon of S. Giorgio in Velabro | 1261, December 17 | Urban IV | |
| Giordano dei Conti Pironti da Terracina† | Roman | Cardinal-deacon | Deacon of Ss. Cosma e Damiano | 1262, May 22 | Urban IV | Died in October 1269, Vice-chancellor |
| Matteo Orsini Rosso | Roman | Cardinal-deacon | Deacon of S. Maria in Portico | 1262, May 22 | Urban IV | Nephew of Pope Nicholas III |
| Elector | Nationality | Order | Title | Elevated | Elevator | Notes |
|---|---|---|---|---|---|---|
| Raoul Grosparmi† (Rodolphe de Chevriêres) | French | Cardinal-bishop | Bishop of Albano | 1261, December 17 | Urban IV | He accompanied king Louis IX of France in his crusade in Tunisia and died there on August 11, 1270 |
| Bernard Ayglerius, O.S.B. | French | Unknown (priest or deacon) | unknown title | 1265 or 1268 | Clement IV | Clement IV's only cardinal creation Some scholars doubt whether he was created cardinal |
The cardinals began the election by meeting and voting once a day in the Viterbo Cathedral before returning to their respective residences; tradition dictated that the election should take place in the Cathedral of the city where the previous pope died, if the late pontiff had died outside Rome. After two months, the cardinals nearly elected Philip Benizi, general of the Servite Order, who had come to Viterbo to admonish the cardinals, but fled to prevent his election. Charles of Anjou was in Viterbo for the entirety of the election; Philip III of France visited the city in March 1271.
In late 1269, after several months of deadlock during which the cardinals had met only intermittently, Ranieri Gatti, the Prefect of Viterbo, and Albertus de Montebono, the Podesta, ordered (some sources say, at the urging of Saint Bonaventure) the cardinals sequestered in the Palazzo dei Papi di Viterbo until a new pope was elected. On June 8, 1270, the cardinals addressed a Diploma to the two magistrates asking that Enrico Bartolomei de Susa, Cardinal-Bishop of Ostia, be dismissed from the "Palatio discooperto" ("the uncovered Palace") owing to his ill health and his having already renounced his right to vote. Some sources say that a makeshift roof was reassembled after the cardinals threatened to put the entire city of Viterbo under interdict.
| Country | Number of Electors |
|---|---|
| France† | 7 |
| Rome† | 6 |
| England, Florence, Genoa, Hungary†, Naples, Padua, Siena | 1 |
| † one cardinal died before final scrutiny | |
The techniques employed against the dilatory cardinals in Viterbo formed the basis for the canonical laws of papal conclaves as laid out in the apostolic constitution, Ubi periculum, of Pope Gregory X, promulgated during the Second Council of Lyon on July 7, 1274 (or 16). Popular accounts of the conclave, as early as those of French historian Georges Goyau, neglect to mention the political intrigue of Charles of Anjou or his nephew, Philip III of France, as the masterminds of the hardships employed by the "citizens of Viterbo."
Designed both to accelerate future elections and reduce outside interference, the rules of Ubi periculum provide for the cardinal electors to be secluded for the entirety of the conclave, including having their meals passed through a small opening, and for their rations to be reduced to a single meal at the end of three days, or bread and water (with a little wine) after eight days. Cardinals also do not collect from the Apostolic Camera any payments they might otherwise receive during the conclave.
The stringent rules of Ubi periculum were used in the conclaves that elected Pope Innocent V (January 1276) and Pope Adrian V (July 1276), lasting one and nine days respectively. However, at the urgings of the College, the newly-elected Adrian V suspended the constitution on July 12, 1276—indicating that he wished to revise it—and died on August 18, without having promulgated a revised version.
Therefore, the election of Pope John XXI (August-September 1276) did not follow Ubi periculum, and—once elected—John XXI promulgated a bull, Licet felicis recordationis, formally revoking Ubi periculum. The next five papal elections—1277 (Pope Nicholas III), 1280—1281 (Pope Martin IV), 1285 (Pope Honorius IV), 1287—1288 (Pope Nicholas IV), and 1292—1294 (Pope Celestine V)—occurred sans conclave, often at great length. Celestine V, whose election took two years and three months, reinstated the conclave with a series of three decrees, and his successor, Pope Boniface VIII restored the conclave into the Code of Canon Law.