Pope Nicholas III (; – 22 August 1280), born Giovanni Gaetano Orsini,George L. Williams, Papal Genealogy: The Families and Descendants of the Popes, (McFarland & Company Inc., 1998), 36. Richard Sternfeld, Der Kardinal Johann Gaëtan Orsini, in a separate Excursus I, pp. 315–316, argues for a date of birth around 1216. He points out that one must take into account that Giovanni Gaetano's mother was a first wife. was head of the Catholic Church and ruler of the Papal States from 25 November 1277 to his death on 22 August 1280.

He was a Roman nobleman who had served under eight popes, been made Cardinal-Deacon of St. Nicola in Carcere Tulliano by Pope Innocent IV (1243–1254), protector of the Franciscans by Pope Alexander IV (1254–1261), inquisitor-general by Pope Urban IV (1261–64), and succeeded Pope John XXI (1276–1277) after a six-month vacancy in the Holy See resolved in the papal election of 1277, largely through family influence.

Personal life Giovanni Gaetano Orsini, was born in Rome,Richard Sternfeld, Der Kardinal Johann Gaëtan Orsini, p. 1. a member of the prominent Orsini family of Italy, the eldest son of Roman nobleman Matteo Rosso OrsiniMatteo Rosso Orsini was a member of the Third Order of S. Francis (Tertiary): Richard Sternfeld, Der Kardinal Johann Gaëtan Orsini, p. 2. It was Giovanni Gaetano's father, also called Matteo Rosso Orsini ('Il Grande'), who, as Senator of Rome, locked the Cardinals up in a sort of proto-conclave in August, 1241. Ryccardus de S. Germano, Chronica. by his first wife, Perna Caetani. His father was Lord of Vicovaro, Licenza, Cantalupo, Roccagiovine, Galera, Formello, Castel Sant'Angelo di Tivoli, Nettuno, Civitella, Bomarzo, San Polo and Castelfoglia, of Nerola from 1235; Lord of Mugnano, Santangelo and Monterotondo; Senator of Rome 1241–1243.

His brother Giordano was named Cardinal Deacon of San Eustachio by Nicholas III on 12 March 1278. His brother Gentile became Lord of Mugnano, Penna, Nettuno and Pitigliano. Another brother, Matteo Rosso of Montegiordano, was Senator of Rome (probably) in 1279, War Captain of Todi, and Podestà of Siena in 1281. There were five other younger brothers and two sisters.

The Orsini family had already produced several popes: Stephen II (752–757), Paul I (757–767) and Celestine III (1191–1198).Williams, Papal Genealogy, p. 215.

He did not, as some scholars used to think, study at Paris—though his nephew did.Demski, p. 7. Sternfeld, p. 3, n. 8. His career shows no indication that he was a legal professional or a theologian. He never became a priest, until he became pope in 1277.

Cardinalate

Giovanni Gaetano Orsini was one of a dozen men created a cardinal by Pope Innocent IV (Sinibaldo Fieschi) in his first Consistory for the creation of cardinals, on Saturday, May 28, 1244, and was assigned the Deaconry of San Nicola in Carcere.Conrad Eubel, Hierarchia catholica medii aevi I, editio altera (Monasterii 1913), p. 7. A. Demski, Papst Nikolaus III. Eine Monographie (Münster 1903), p. 8 and n. 2. He was a Canon and Prebendary of York,Potthast, no. 21268. and also of Soissons and Laon.Demski, p. 9 n. 2. In the summer of 1244, he was one of five cardinals who fled to Genoa with Pope Innocent IV.August Potthast, Regesta Pontificum Romanorum II (Berlin 1875), 11459–11460 (September 27–28, 1244); A. Demski, Papst Nikolaus III. Eine Monographie (Münster 1903), p. 9. He was at Lyon,Potthast, no. 11518 (July 23, 1145). and was present in June and July for the Ecumenical Council of Lyon.Potthast, no. 11729 (July 15), no. 11749 (July 23), and no. 11750 (July 24). Cardinal Orsini and the Curia did not return to Italy until May 1251—after the death of Emperor Frederick II Hohenstaufen. After spending the summer in Genoa, Milan and Brescia, they finally reached Perugia in November 1251, where the Papal Court resided continuously until April 1253.A. Parracivini Bagliani, "La mobilità della curia romana nel secolo XIII. Reflessi locali", in Società e istituzioni dell' Italia communale: l' esempio di Perugia (Secoli XII–XIV) (Perugia 1988) 155–278.

The Curia returned to Rome in mid-October, where Pope and Curia resided continually until the end of April, 1254. In May they went on pilgrimage to Assisi, then visited Anagni, where the Court stayed from June until the second week in October, when they went off in pursuit of Manfred, Hohenstaufen regent of the Kingdom of Sicily. At the beginning of December, the Battle of Foggia took place, and the papal army was routed. Innocent IV died in Naples, where he had taken refuge, on 7 December 1254, and the meeting to elect his successor was therefore held in Naples in the palace in which he had died. Voting began on Friday, 11 December, with ten of the twelve cardinals present, but no candidate received the required votes. But on Saturday, 12 December, Cardinal Rinaldo dei Conti di Segni, the nephew of Pope Gregory IX, who had a reputation of a conciliator, was elected pope. He chose to be called Alexander IV and was crowned on Sunday, December 20, 1254, in the Cathedral of Naples. As for Cardinal Giovanni Gaetano Orsini, in his first eleven and a half years as a cardinal, he had only spent six months in the city of Rome. A peripatetic Curia had its disadvantages.

Pope Alexander IV and the Curia continued to live in Naples, until the first week of June 1255 when they returned to Anagni, and it was not until mid-November that the Pope was back in Rome. There the Curia stayed until the end of May, 1256, when it was off to Anagni for the summer, until the beginning of December. The problem was that Rome was in the hands of Senator Brancaleone degli Andalo, Count of Casalecchio, and the Ghibellines since 1252, and Alexander was repeatedly driven out by unruly mobs.Gregorovius History of the City of Rome in the Middle Ages V.1, 280–299; 310–311; 317–324, Karl Hampe, Urban IV und Manfred (1261–1264) (Heidelberg: Carl Winter 1905), p. 13. Giuseppe Rovere, Brancaleone degli Andaló senatore di Roma: contributo alla storia del comune di Roma nel Medio Evo (Udine 1895). Girolamo Giuliani, Il comune di Roma sotto il senatorato di Brancaleone degli Andalò (1252–1258) (Roma 1957). Rome was home again until the end of May, 1257, until the summer vacation at Viterbo began. The vacation lasted until the end of October, 1258, when the Court visited Anagni again; they stayed until the beginning of November, 1260. The Pope then was able to reside at the Lateran until the first week of May, 1261, when the Court was off to Viterbo again. Alexander IV died at Viterbo on 25 May 1261. Nineteen months were spent in Rome, out of a total of seventy-eight. Alexander had created no new cardinals, and so the Electoral meeting following his death had only eight participants. The Election was a long-drawn-out one, lasting from 25 May to 29 August 1261. Unable to agree on one of themselves, the Cardinals chose Jacques Pantaléon, the Latin Patriarch of Jerusalem, who, since 1255, was Papal Legate with the Crusade in the Holy Land. He became Pope Urban IV, and was crowned at Viterbo on 4 September 1261.

Cardinal Orsini was named General Inquisitor by Urban IV on November 2, 1262,Fr. Joannis Hyacinthi Sbarale,Bullarium Franciscanum II, p. 453; Potthast, no. 18422. the first known Grand Inquisitor.J. B. Sägmüller, Thätigkeit und Stellung der Kardinale bis Papst Bonifaz VIII. (Freiburg im Breisgau: Herder 1896) p. 111.

Cardinal Orsini attended the first Conclave of 1268–1271, and was one of the cardinals who signed the letter of complaint against the authorities and people of Viterbo for their treatment of the cardinals and the Curia. He was one of the six cardinals who were chosen by the rest of the Sacred College on September 1, 1271, to select a compromise candidate for election as pope. He was therefore instrumental in bringing to the papal throne the Archdeacon of Liège, Teobaldo Visconti, who was not a cardinal, and who was not even in Italy, but in the Holy Land on crusade. He traveled with the Curia to France in 1273, and was present at the Ecumenical Council of Lyon. He was not one of the cardinals in the suite of Pope Gregory X when he left Lyon in 1275 to return to Rome, nor was he at Arezzo where the Pope died on 10 January 1276, before reaching the city. He did not attend the first conclave which began on 20 January 1276, and concluded the next day with the election of Peter of Tarantaise, who became Pope Innocent V.He was consecrated bishop and crowned pope at the Vatican Basilica on 22 February Pope Innocent V (Peter of Tarantaise) died in Rome at the Lateran, on 22 June 22, 1276.

The second Conclave of 1276 began, therefore, according to the rules set down by Pope Gregory X, on July 2. Thirteen cardinals were present, including Giovanni Gaetano Orsini. King Charles I of Sicily acted as the Governor of the Conclave, in which position he is said to have been rigorous, but understandably partisan in favor of the French faction. Cardinal Ottobuono Fieschi of Genoa was elected on July 11 and chose the name Pope Adrian V.Gregorovius, pp. 474–475. Demski, pp. 34–37. Sternfeld, pp. 251–263. He lived only thirty-nine days longer, dying at Viterbo, where he had gone to meet King Rudolf and avoid the summer heat of Rome. According to Bernardus Guidonis, he was never ordained priest, consecrated bishop or crowned pope (nondum promotus in sacerdotem nec coronatus nec consecratus)."Life of Adrian V", in Ludovico Muratori, Rerum Italicarum Scriptores III, 605. His one memorable act was to suspend the Constitution of Gregory X "Ubi periculum" which regulated conclaves. He intended, on the advice of his cardinals, to improve Gregory's regulations. Cardinal Orsini was present at the discussion and decision. Shortly after his accession, moreover, Pope Adrian V had wanted King Charles I of Sicily to come to Viterbo to carry out the usual fealty, and sent the Suburbicarian Bishop of Sabina (Bertrand de Saint Martin); Cardinal Giovanni (Orsini), Cardinal Deacon of St. Nicola in Carcere Tulliano; and Cardinal Giacomo (Savelli), Cardinal Deacon of Santa Maria in Cosmedin, to effect his wishes. Charles arrived in Viterbo from Rome on July 24. Unfortunately, Pope Adrian died, on August 18, leaving his negotiations with King Charles unfinished.F. Cristofori, Le tombe dei pape in Viterbo (Siena 1887), p. 175.

The third Conclave of 1276 began at the beginning of September in Viterbo, where Adrian V had died. The opening ceremonies, which should have taken place on August 29, had to be delayed for several days because of the riotous behavior of the people of Viterbo. Since Pope Adrian had created no new cardinals, the number of cardinals was twelve; Cardinal Simon de Brion was still in France, serving as Papal Legate. Once the tumults had been put down, however, the cardinals did their business quickly. On September 8, 1276, the senior Cardinal-Bishop, Peter Julian of Lisbon, was elected on the first ballot. He chose to be called John XXI, and on September 20 he was crowned at the Cathedral of San Lorenzo in Viterbo by Cardinal Giovanni Caetano Orsini. Since John XXI was already a bishop, there was no ordination or consecration necessary. He was the fourth pope of 1276. On 18 October, Cardinal Giovanni Gaetano Orsini was appointed Archpriest of St. Peter's, in place of Cardinal Riccardo Annibaldi, who had recently died, and who may have been too ill to participate in the Conclave or the Coronation.Potthast, no. 21171.