Following the death of Benedict XI in 1304, he was elected Pope Clement V in June 1305 (and was consecrated on 14 November), after a year's interregnum occasioned by the disputes between the French and Italian cardinals, who were nearly equally balanced in the conclave, which had to be held at Perugia. Bertrand was neither Italian nor a cardinal, and his election might have been considered a gesture towards neutrality. The contemporary chronicler Giovanni Villani reports gossip that he had bound himself to King Philip IV of France (1285–1314) by a formal agreement previous to his elevation, made at St. Jean d'Angély in Saintonge. Whether this was true or not, it is likely that the future pope had conditions laid down for him by the conclave of cardinals. At Bordeaux, Bertrand was formally notified of his election and urged to come to Italy; but he selected Lyon for his coronation, November 14, 1305, which was celebrated with magnificence and attended by Philip IV. Among his first acts was the creation of nine French cardinals.
Early in 1306, Clement V explained away those features of the bulls Clericis Laicos that might seem to apply to the King of France and essentially withdrew Unam Sanctam, the two bulls of Boniface VIII which were particularly offensive to Philip IV's ambitious ministry. He appears to have conducted himself throughout his pontificate as the mere tool of the French monarchy, a radical change in papal policy.
On October 13, 1307, came the arrest of hundreds of the Knights Templar in France, an action apparently financially motivated and undertaken by the efficient royal bureaucracy to increase the prestige of the crown. Philip IV was the force behind this ruthless move, but it has also tarnished the historical reputation of Clement V. From the very day of Clement V's coronation, the King had charged the Templars with heresy, immorality and abuses, and the scruples of the Pope were compromised by a growing sense that the burgeoning French State might not wait for the Church, but would proceed independently.
In March 1309 the entire papal court moved from Poitiers (where it had remained for 4 years) to Avignon, which was not then part of France but an imperial fief held by the King of Sicily. The removal of the Papacy to Avignon was justified at the time by French apologists on grounds of security, since Rome, where the dissensions of the Roman aristocrats and their armed militia had reached a nadir, and where the Basilica di San Giovanni in Laterano had been destroyed in a fire, was unstable and dangerous. But the decision proved the precursor of the long Avignon Papacy, the 'Babylonian captivity' (1309–77), in Petrarch's phrase, and marks a point from which the decay of the strictly Catholic conception of the pope as universal bishop may be dated.
Meanwhile, Philip IV's lawyers pressed to reopen Nogaret's charges of heresy against the late Boniface VIII that had circulated in the pamphlet war around Unam sanctam. Clement V had to yield to pressures for this extraordinary trial, begun February 2, 1309, at Avignon, which dragged on for two years. In the document that called for the witnesses, Clement V expressed both his personal conviction of the innocence of Boniface VIII and his resolution to satisfy the King. Finally, in February, 1311, Philip IV wrote to Clement V abandoning the process to the future council of Vienne. For his part, Clement V absolved all the participants in the abduction of Boniface at Anagni.
In pursuance of the King's wishes, Clement V summoned the Council of Vienne (1311), which refused to convict the Templars of heresy. The Pope abolished the order anyway, as the Templars seemed to be in bad repute and had outlived their usefulness as papal bankers and protectors of pilgrims in the East. Their French estates were de jure granted to the Knights Hospitallers, but Philip IV held them until his death and expropriated the Templar's bank outright.
Charges of heresy and sodomy aside, the guilt or innocence of the Templars is one of the more difficult historical problems, partly because of the atmosphere of hysteria that had built up in the preceding generation and the habitually intemperate language and extravagant denunciations exchanged between temporal rulers and churchmen, and partly because the subject has been embraced by conspiracy theorists and pseudo-historians.
Clement V's pontificate was also a disastrous time for Italy. The Papal States were entrusted to a team of three cardinals, but Rome, the battleground of the Colonna and Orsini factions, was ungovernable. In 1310, the Emperor Henry VII (1308–13) entered Italy, established the Visconti as vicars in Milan, and was crowned by Clement V's legates in Rome (1312) before he died near Siena in 1313.
In Ferrara papal armies clashed with Venice. When excommunication and interdict failed to have their intended effect, Clement V preached a crusade against the Venetians, a symptom of how polarized that particular conflict had become.
Other remarkable incidents of Clement V's reign are his violent repression of the Fra Dolcino, which he considered a heresy, in Lombardy and his promulgation of the Clementine Constitutions in 1313. He died in April 1314. According to one story, while his body was lying in state, a thunderstorm developed during the night and lightning struck the church where his body lay, igniting the building. The fire was so intense that, when it was extinguished, the body of Pope Clement V was almost completely destroyed. He is buried at La Chaise-Dieu in Auvergne.
On April 4, 1312, a Crusade was promulgated by Pope Clement V at the Council of Vienne. Another embassy was sent by Oljeitu to the West and to Edward II in 1313. In 1313, the French king Philip the Fair "took the cross", making the vow to go on a Crusade in the Levant, thus responding to Clement V's call. Philip was warned against leaving by Enguerrand de Marigny, and died soon after in November 1314 in a hunting accident.