Pope Gregory X accepts Michael's offer of union at its face value.

Rudolph of Habsburg, to win the approbation of Pope Gregory X, had renounced all imperial rights in Rome, the papal territory, and Sicily, and promised to lead a new crusade.

The Pope, in spite of Ottokar II of Bohemia's protests, not only recognizes Rudolph himself, but persuades King Alfonso X of Castile (another grandson of Philip of Swabia), who had been chosen German (anti-)king in 1257 as the successor to Count William II of Holland, to do the same.

Thus, Rudolph surpasses the two heirs of the Hohenstaufen dynasty that he had earlier served so loyally, and succeeds in saving the Holy Roman Empire from disintegrating by promoting the election of Rudolf I of Habsburg as emperor.

At the same time, he keeps the peace with King Charles I of Naples, who also has claims on the imperial throne.

In return for his support, Gregory makes Rudolph promise to lead a new crusade and to renounce claims on behalf of the Holy Roman Empire in Rome and the papal territories.

Pope Gregory X decrees in 1274 that conclaves (meetings during which the electors have no contact with the outside) should be used for papal elections, reforming the electoral process which had taken over three years to elect him.

In this same year, he issues a bull denying the existence of ritual murders by Jews.

Following his pleas at the Council of Lyons in 1274, Gregory discovers that, although Europe is aware of the gravity of the Eastern situation, it is both unwilling and unable to give substantial aid.

The ineffectiveness of the Jerusalem administration is becoming apparent even to Easterners, and the Il-Khan Abaqa sends his deputy Rabban Sauma to the kings of Europe and the Pope to seek an alliance.

The effort is fruitless.

The new Pope, dependent on Charles of Anjou in nearly everything, quickly appoints him to the position of (Western) Roman Senator.

At the insistence of Charles, Martin IV excommunicates the Eastern Roman Emperor Michael VIII Palaiologos, who stands in the way of Charles's plans to restore the Latin Empire of the East that had been established in the aftermath of the Fourth Crusade.

He thus breaks the tenuous union that had been reached between the Greek and the Latin Churches at the Second Council of Lyons in 1274 and further compromise is rendered impossible.

At the same time, Martin IV authorizes a Crusade against the newly reestablished “schismatic” Empire in Constantinople.

The Sicilians, after electing Peter III of Aragon as their king, seek papal confirmation in vain, though they are willing to reconfirm Sicily as a vassal state of the papacy.

Martin IV uses all the spiritual and material resources at his command against the Aragonese in order to preserve Sicily for the House of Anjou.

The Pope excommunicates Peter and declares that he has forfeited the kingdom of Aragon, which has been a papal fief since the eleventh century, and orders a crusade against him.

Martin invites Philip to take control of Aragon and offers him the vacant throne for one of his sons.

The Angevins are supported by the papacy, the Italian Guelphs, and Philip III of France, Charles's nephew, while the Aragonese are helped by the Italian Ghibellines.

The ensuing War of the Sicilian Vespers will sharply diminish Angevin power in the Mediterranean.

The former Norman domains on the mainland remain under Angevin rule as the Kingdom of Naples.

Peter III obtains the support of Nasrid Granada in preparation for the incoming Aragonese Crusade led by Philip of France.

Pope Martin IV, having declaring that Peter III has forfeited his right to rule Aragon because of his supposed conspiratorial intervention in Sicilian affairs, and excommunicated him, now offers the Aragonese kingdom (under the vassalage of the Holy See) to Charles of Valois, the fourth son of King Philip III of France and Isabella of Aragon, and urges the French to launch a crusade against Peter.

Moderately intelligent, disproportionately ambitious and quite greedy, Charles is a son, brother, brother-in-law and son-in-law of kings or of queens (of France, of Navarre, of England, and of Naples).

He thus dreams of more and will seek all his life for a crown he will never obtain.

Pope Martin’s successor, Cardinal Giacomo Savelli, born in Rome into the rich and influential family of the Savelli, had studied at the University of Paris, where he held a prebend and a canonry at the cathedral of Châlons-sur-Marne.

Later he obtained the benefice of rector at the church of Berton in the Diocese of Norwich in England, a nation he never visited.

In 1261 he was created Cardinal Deacon of Santa Maria in Cosmedin by Pope Urban IV, who also appointed him papal prefect in Tuscany and captain of the papal army.

Cardinal Savelli pursued a diplomatic career.

Pope Clement IV sent him and three other cardinals to invest Charles of Anjou as King of Sicily at Rome on July 28, 1265.

After the long deadlocked vacancy in the papal see after the death of Clement IV, a vacant seat of three years, he was one of the six cardinals who finally elected Pope Gregory X by compromise on September 1, 1271 in a conclave held at Viterbo because conditions in Rome were too turbulent.

He accompanied Gregory X to the Council of Lyon in 1274, where it was established that only four mendicant orders were to be tolerated: Dominicans, Franciscans, Augustinians and Carmelites.

In July 1276, he was one of the three cardinals whom Pope Adrian V sent to Viterbo with instructions to treat with the German King, Rudolf I of Habsburg, concerning his imperial coronation at Rome and his future relations towards Charles of Anjou, whom papal policy supported.

The death of Adrian V in the following month rendered the negotiations with Rudolf fruitless.

He became Protodeacon of the Sacred College in November 1277 and as such, he crowned Popes Nicholas III on December 26, 1277 and Martin IV on March 23, 1281.

When Martin IV died o March 28, 1285, at Perugia, Cardinal Savelli is unanimously elected Pope on May 20 and takes the name of Honorius IV.

His election is one of the speediest in the history of the papacy.

On the same day that he is elected, he is consecrated bishop and crowned Pope in the Basilica of St. Peter.

Honorius IV is already advanced in age and so severely affected with gout that he can neither stand nor walk.

When saying Mass he is obliged to sit on a stool and at the elevation of the host his hands have to be raised by a mechanical contrivance.

In this year also, Arnolfo di Cambio produces the giant altar canopies (ciboria, or baldachinos) in Rome’s “San Paolo fuori le Mura” (“St. Paul's Outside the Walls”).

Charles of Anjou has left his captive son Charles as his natural successor.

Honorius IV, more peaceably inclined than Martin IV, had not renounced the Church's support of the House of Anjou, nor had he set aside the severe ecclesiastical punishments imposed upon Sicily.

On the other hand, he does not approve of the tyrannical government the Sicilians had been subject to under Charles of Anjou.

This is evident from legislation embodied in his constitution of September 17, 1285 (Constitutio super ordinatione regni Siciliae), in which he states that no government can prosper that is not founded on justice and peace.

He passes forty-five ordinances intended chiefly to protect the people of Sicily against their king and his officials.