Born to a noble family, Sergius was educated in the schola cantorum and ordained cardinal-priest of the Church of Sts.
[1] At a preliminary meeting to designate a successor to Gregory IV, who died in January 844, Sergius was nominated by the aristocracy, while the people of Rome declared for the deacon John.
[1] Emperor Lothair I, however, disapproved of this abandonment of the Constitutio Romana of 824, which included a statute that no pope should be consecrated until his election had imperial approval.
The Church and the emperor reached an accommodation, with Sergius crowning Louis as king,[2] but the pope did not accede to all the demands made upon him.
[3] During his pontificate, the outskirts of Rome were ravaged, and the churches of St. Peter and St. Paul were sacked by Arabs, who also approached Portus and Ostia in August 846.