Background and elevation as pope
The town of Nepi
, where Constantine II was born
Constantine was born into a noble Roman family in Nepi near Viterbo. He was one of four brothers, of which the most prominent was Toto of Nepi. Toto, the papal governor and self-styled "Duke" of Nepi, began to position himself to take advantage of the expected death of Pope Paul I, and elevate his own candidate onto the papal throne. Christophorus, the Primicerius of the notaries, forced Toto to take an oath to respect the traditional clerical method of papal elections. Toto, however, having retired to his estates in Nepi, with the help of Constantine and his other brothers collected troops from his duchy and other parts of Tuscany, in addition to arming a group of peasants to swell the numbers.
On 28 June, hearing that Pope Paul was on the verge of dying, Toto and his armed men forced their way into the city through the Gate of St. Pancratius. With Paul’s death, Toto made his way to the Basilica of the Apostles where the other members of the papal court and Roman nobility were gathering, and there Christophorus had everyone swear that they would all uphold each other’s rights during the upcoming election. However, as soon as the meeting had broken up, Toto’s armed retainers had assembled in his house at Rome and elected his brother Constantine as pope.
Since Constantine was still a layperson, he needed to be ordained deacon and priest and then consecrated as bishop in rapid succession. Although frowned upon by canon law, this approach was far from unknown at the time. Therefore, accompanied by a group of armed men, he was escorted to the Lateran Palace, where they attempted to force George, the Bishop of Praeneste, to ordain Constantine as a monk. George threw himself at Constantine’s feet, begging Constantine not to make him do this. However, Constantine and his supporters made it clear that he would be forced to, one way or another. George therefore performed the ceremony, ordaining Constantine as a monk. The next day, 29 June, Bishop George made Constantine a subdeacon followed immediately by his elevation to deacon. This contravened canon law, which required an interval between the giving of the major orders of at least one day.
The Roman people were then required to take an oath of fidelity to Constantine, who again forced George of Praeneste, together with bishops Eustratius of Albano and Citonatus of Porto, to consecrate him as Bishop of Rome on 5 July 767. In the meantime, opposition to the antipope was being led by Christophorus, the Primicerius, and his son Sergius, the treasurer of the Roman church. Noting, however, that their lives were in danger, they fled for sanctuary to St. Peter’s Basilica, where they remained until April 768.