In 1276 and 1277 there were five popes and four conclaves. Pope Innocent V (Peter of Tarantaise) died on June 22, 1276 in Rome. It is said, by the brother of Mateo de Romano, in the Annales Veronenses (p. 418), that the pope was poisoned:
Item eodem anno  die dominico VII intrante Junio, Innocencio pape quinto datum fuit venenum, et dicebatur quod rex Karolus hoc fieri fecerat, qui erat Rome, set bene evasit de ipso tosico. item eodem anno die lune VIIII exeunte Junio [June 22] mortuus est Innocentius papa quintus.
This charge is repeated in the Annals of S. Martialis of Limoges (MGH SS XXIV , p.440). Innocent V was buried in the Lateran Basilica, and King Charles erected a magnificent porphyry tomb in his honor. Innocent had created no new cardinals during his pontificate. Pope Gregory X's regulations for the conduct of a conclave Ubi Periculum, promulgated at the Second Council of Lyons, were still in force. The papal throne was vacant for 18 days.
.At the time of Innocent's death, there were thirteen or fourteen cardinals, though
There were, therefore, thirteen electors present at the Conclave in Rome::
King Charles I of Sicily was in Rome from January 8, 1276 (two days before Pope Gregory X died) through July 20 (after the election of Adrian V–who was never crowned), except for a brief visit to Viterbo on February 9, and to Macerata on June 5 (Durrieu, 179-180)..
The conclave began on July 2, 1276 and lasted ten days. Eight votes were needed to elect a pope. No records of what took place have survived, though one may surmise that the choice was not easy or obvious. King Charles of Sicily, the Senator of Rome, acted as governor of the Conclave. His administration was exceedingly rigorous, though unfair in his favoring the French faction (Gregorovius, 474-475). Ottobono Fieschi, who had been a cardinal for twenty-five years, and who had recently helped bring an end to the civil strife in Genoa, was elected pope on July 11. He took the name Adrian V, and ruled the Church for 39 days. According to Bernardo di Guidone, nondum promotus in sacerdotem nec coronatus nec consecratus Viterbi moritur (He was never ordained priest, consecrated bishop or crowned pope.) (Muratori, Rerum Italicarum Scriptores III, 605; Novaes, 261; Montor, 47).
In August he travelled to Viterbo, partly for the climate and partly to attend to some differences between the Church and Emperor Rudolph of Habsburg. The ten days he and the other cardinals spent in the conclave under the rules of Gregory X must have had their effect; at the request of the cardinals in consistory, he suspended the operation of Gregory X's constitution on conclaves, intending to make some alterations and improvements (Montor, 46). The bull is extant in which John XXI abrogates the regulations of Gregory X and mentions their suspension by Adrian V (Tomassetti, Bullarium Romanum IV, pp. 37-38):
Licet felicis recordationis Gregorius Papa praedecessor noster, pia meditatione considerans quantum sit onusta dispendiis, plenaque periculis Ecclesiae Romanae prolixa vacatio: et vigilanter intendens, super hoc de opportuno remedio providere, quandam super electione Romani Pontificis constitutionem ediderit in concilio Lugdunensi; quia tamen experientia docuit, constitutionem eandem multa intolerabilia, nonnulla obscura et propter hoc accelerationi provisionis eiusdem Ecclesiae valde damnosa, immo etiam provisionis ipsius impedimenta et dilationem ingerentia continere; piae memoriae Adrianus Papa praedecessor noster, diligenter lpraemissa considerans et residens in camera sua Lateranensi, in consistorio, nobis et aliis fratribus suis, de quorum numero tunc eramus, praesentibus; bonae memoriae V[icedomino de Vicedomini] Praenestino episcopo, V. [Uberto D' Elci] S. Eustachii diacono, et dilectis filiis G[Guillaume de Bray] tit. S. marci presbytero tunc infirmitate detentis, ac S(imon Mompitié de Brie) tituli S. Caeciliae Apostolicae Sedis legato, presbytero, cardinalibus dumtaxat exceptis, constitutionem eandem, quoad omnem ipsius effectum, quidquid posset contingere, solemniter et absolute suspendit; the quamvis post eius obitum nos et dicti fratres, qui tunc supererant, et praesentes etiam in Romana Curia, suspensionem huiusmodi non solum verbis, sed litteris etiam nostro et eorundem sigillis nomitis, concorditer testaremur; nonnulli tamen corda contumacia in damnatam superbiam erigentes, adhibere fidem nostro testimonio tontempserunt; alias etiam infrunitis animis suggerentes huiusmodi nostro testimonio non esse credendum; quamquam insuper aliquorum habet assertio, eundem praedecessorem Adrianum in lecto aegritudinis decumbentem suspensionem revocasse praedictam; nos tamen et iidem fratres frequentes et diligentes super hoc inter nos collationes habuimus; et non solum ab iis, qui revocationis huiusmodi conscii dicebantur, sed ab aliis eiusdem praedecessoris Adriani familiaribus et aliis etiam studuimus veritatem frequentissime indagare; nec invenimus eundem praedecessorem Adrianum ad revocationem praedictam aliquatenus verbo vel literis processisse....
On his deathbed, it was said, Adrian retracted his suspension order, though there were some who disbelieved even the sworn testimony of the Cardinals that it was not true. Death supervened, after a reign of thirty-nine days. Pope Adrian V (Fieschi) was buried in Viterbo, in the Church of S. Francesco (Cristofori, 137-185).
The Brother of Mateo de Romano: Monumenti storici publicati dalla R. Deputazione Veneta di storia patria. Serie terza. Cronache e diarii, Vol. II. Antiche Cronache Veronesi (Venezia 1890), pp. 409-469 "Annales Veronenses"
Onuphrio Panvinio, Epitome Pontificum Romanorum a S. Petro usque ad Paulum IIII. Gestorum (videlicet) electionisque singulorum & Conclavium compendiaria narratio (Venice: Jacob Strada 1557). Lorenzo Cardella, Memorie storiche de' cardinali della Santa Romana Chiesa Tomo primo, parte secondo (Roma: Pagliarini 1792). Ludovico Antonio Muratori, Annali d' Italia Volume 18 (Firenze 1827). Giuseppe de Novaes, Elementi per la storia de' Sommi Pontefici terza edizione Volume III (Roma 1821). G. Moroni, Dizionario di erudizione storico-ecclesiastica Volume 1 (Venezia 1840) 104. Paul Durrieu, Étude sur les registres angevines du Roi Charles Ier Tome second (Paris 1888), 179-180. Francesco Cristofori, Le tombe dei pape in Viterbo (Siena 1887). F.Gregorovius, History of Rome in the Middle Ages, Volume V.2 second edition, revised (London: George Bell, 1906) 474-475. Richard Sternfeld, Der Kardinal Johann Gaetan Orsini (Papst Nikolaus III.) 1244-1277 (Berlin: E. Ebering 1905) 251-263. N. Schopp, Papst Hadrian V (Heidelberg 1916) 222.
On Bernard Ayglier, OSB, abbot of Montecassino, see: Luigi Tosti, OSB, Storia della Badia di Monte-cassino Tomo III (Napoli 1843) 6-32; 65-89
On Vicedomino de' Vicedomini, and the myth of his one-day papacy, see: F. Cristofori, Le tombe dei pape in Viterbo (Siena 1887), 185-202. Novaes, 262. Moroni Dizionario di erudizione storico ecclesiastica 32, 279-280.
Suspension of Gregory X's constitution on papal elections: Adrian V (Ottobono Fieschi) suspended the arrangements of Pope Gregory orally in a consistory: Giordano, quoted in Reynaldi, Annales Ecclesiasticae sub anno 1276. They were officially cancelled by the Bull Licet of Pope John XXI on September 30, 1276. A. Ceccaroni Il conclave (Roma 1901) 57.
On Simon de Brie and the Council of Bourges in September, 1276, see Carl Joseph von Hefele, Conciliengeschichte nach dem Quellen bearbeitet second edition Volume VI (Freiburg im Breisgau: Herder 1890) 176-177.
© 2008 John Paul Adams, CSUN