| Month: | March |
| Year: | 1447 |
| Dates: | 4–6 March 1447 |
| Location: | Santa Maria sopra Minerva, Papal States |
| Dean: | Giovanni Berardi |
| Vicedean: | Francesco Condulmer |
| Camerlengo: | Ludovico Trevisan |
| Protopriest: | Henry Beaufort |
| Protodeacon: | Prospero Colonna |
| Candidates: | Prospero Colonna |
| Pope Elected: | Tommaso Parentucelli |
| Nametaken: | Nicholas V |
| Prevconclave Year: | 1431 |
| Prevconclave Link: | 1431 papal conclave |
| Nextconclave Year: | 1455 |
| Nextconclave Link: | 1455 papal conclave |
The 1447 papal conclave (March 4–6), meeting in the Roman basilica of Santa Maria sopra Minerva, elected Pope Nicholas V (Parentucelli) to succeed Pope Eugene IV (Condulmer).
Eugene IV had died on February 23, 1447.[1] The cardinals entered conclave at the time of Vespers (sunset) on March 4, after waiting the full nine days proscribed by Ubi periculum.[2] Of the twenty-four cardinals living, only eighteen were present in Rome for the conclave.[2] The conclave, like its predecessor which had elected Eugene IV, was held in the Sacristy of the Dominican friars of Santa Maria sopra Minerva, even though many members of the College of Cardinals would have preferred to relocate to the Vatican.[3]
Several Roman barons, most prominent among them Gio Baptista Savelli, insisted for a time on being able to vote in the conclave (although perhaps they only wished to remain present); the Savelli family had been granted the right to guard the conclave by Pope Gregory X, but Gio Baptista wished for the first time to carry out this duty from inside the conclave; the barons were eventually expelled.[3]
Prospero Colonna, the nephew of Pope Martin V and Protodeacon of the Sacred College, was regarded as the leading papabile at the start of the conclave.[3] Colonna received 10 votes (two short of the requisite two-thirds majority) in the first scrutiny, on Sunday, March 5; 8 votes went to Domenico Capranica, and there were five for Parentucelli (Bononiensis).[4] The next day the adherents of Colonna continued to vote for him, while the other eight attempted to peel away votes (unsuccessfully) by switching their choice to others, including the non-cardinal archbishops of Benevento and Florence.[4] Colonna had the support of the French cardinals and those who were impressed with the influence he enjoyed in various Italian city-states, but he did not have the support of the Roman public due to Colonna's use of extrajudicial violence during his uncle's papacy. The people (that is to say, the leaders in Roman politics) preferred Niccolo d'Acciapaccio. Aeneas Silvius Piccolomini, who was one of the Custodians of the Conclave and is a principal source for the event, says merely that on Monday morning, March 6, there was some talk about the Archbishops, and then the scrutiny took place. There seems to be no evidence that they actually received votes.[4]
On March 6, after the first of the two daily scrutinies, during which Colonna again received 10 votes, Cardinal Capranica addressed the conclave, reminding them of the various dangers facing the church, including the armies of the Alfonso, King of Aragon, which were sailing towards Italy, the (now unopposed) reign of Antipope Felix V, Duke of Savoy, as well as a certain "Count Francis" - imploring two more cardinals to throw their support to Colonna.[5] According to Trollope, the cardinals' term for Colonna as "mansuetto agnello" (mild as a lamb) would have been viewed as ironic, given that Colonna had carried off much of the papal treasure on the death of Martin V with the help of his noble relatives, and had for a time been excommunicated by Eugene IV prior to his disgorgement.[6]
Tommaso Parentucelli rose following this speech, and Giovanni Berardi (thinking that his colleague was about to give the election to Colonna) interrupted him and asked for a delay.[7] At this point Ludovico Trevisan, angered at Berardi's blocking of Colonna asked whom Berardi wished to see elected instead.[7] Berardi replied "Bononiensis" (Parentucelli). Parentucelli (misinterpreting, perhaps purposefully, his words) declared that he "too" was willing to give his vote to whoever the choice of Berardi was.[8] "Then, I give my vote for you!" Berardi exclaimed, a move which Trevisan felt obliged to follow.[8] One after another the cardinals threw their support to Parentucelli, with the eleventh vote coming from "Cardinal Marino", and the decisive twelfth vote coming from the "Cardinal of San Sisto".[9]
The eighteen electors were: