Born to the nobility, but little else is known of his early life.
Elected to the papacy and raised to the throne without waiting for approval by emperor Lothar.
Lothar sent an army under his son Louis to enforce the emperor's perogative to approve the choice of pope, but peace was negotiated, and Louis was crowned king of Lombardy by Sergius.
In August 846, Rome and churches of the Vatican were sacked by Saracens.
