In a document of January 1107, he styles himself Ego Petrus Portuensis episcopus gratia Dei et beati Petri apostoli et eiusdem domini nostri papae cardinalis sanctae Romanae et apostolicae sedis atque Rector Beneventanus.
On 12 February the ceremony took place at St. Peter's Basilica, and during the welcome at the door, the pope read out a decree, in which he repudiated lay investiture, and ordered all bishops to surrender their imperial fiefs to the emperor immediately and permanently.
The king and the indignant bishops retired to discuss the shocking demand, and, as evening approached, the pope refused the coronation.
[3] On 18 April, at Ponte Mammolo on the Anio River, Pietro was one of the cardinals who were compelled to sign the papal promise to observe the agreement which Henry had drawn up.
Though asserting the separation of church and state in the institution to benefices, Paschal granted the emperor a privilegium in the matter of investiture.
The leaders of the movement were the papal legate in Aquitaine, Archbishop Gerard of Angoulême; the bishops Leo of Ostia and Galo of St. Pol-de-Leon; and the cardinals Robert of S. Eusebio and Gregory of SS.
[8] At the time of Pope Paschal's death on 21 January 1118, Cardinal Pietro had already been serving as Papal vicar at Rome for a number of years.
Forced to flee Rome because of the violence of the Frangipani and the approach of the army of the Emperor Henry V, Gelasius took refuge in Gaeta, where he was consecrated a bishop and enthroned by three cardinal-bishops, Lamberto of Ostia, Pietro of Porto, and Vitalis of Albano.
Within days, Cardinal Pietro presided over the ratification by the Roman clergy of the election of Pope Calixtus II, which was sent to France in time for him to be enthroned in the cathedral of Vienne on 9 February 1119.
[13] On 6 July 1121, Pope Calixtus II appointed Bishop Pietro his legate in the Holy Land, to carry the pallium to the newly elected and confirmed Patriarch of Jerusalem, Guarmundus.
Seven days later, stricken with guilt and remorse, Lamberto resigned his false papacy, though the cardinals apparently reelected or confirmed his office.
[22] Honorius II died in Rome in the monastery of S. Gregory on the Clivus Scauri, near the Colosseum, on 13 February 1130, after a protracted illness.
[29] Depriving Petrus Senex and three other cardinal-bishops of their right to deliberate and vote was a violation of Nicholas II's constitution In nomine Domini.
Neither did they inform the magistrates of the city of Rome, who only learned of the fact when they assembled after dawn at the church of S. Marco to pay a collective call on the pope.
After dawn, the senior-cardinal bishop, Petrus Senex, met with the other cardinals, the important Roman clergy, the magistrates and leading citizens, and the people of Rome, in anticipation of the possible announcement of the death of the pope.