With imperial support, Gerbert was elected to succeed Gregory V as pope in 999. Gerbert took the name of Sylvester II, alluding to Sylvester I (314–335), the advisor to Emperor Constantine I (324–337). Soon after he became pope, Sylvester II confirmed the position of his former rival Arnulf as archbishop of Rheims. As pope, he took energetic measures against the widespread practices of simony and concubinage among the clergy, maintaining that only capable men of spotless lives should be allowed to become bishops. In 1001, the Roman populace revolted, forcing Otto III and Sylvester II to flee to Ravenna. Otto III led two unsuccessful expeditions to regain control of the city and died on a third expedition in 1002. Sylvester II returned to Rome soon after the emperor's death, although the rebellious nobility remained in power, and died a little later. Sylvester is buried in St. John Lateran.