Григорий V
In 996, Otto III marched to Italy to claim the titles of King of Italy and Holy Roman Emperor, which had been left unclaimed since the death of Otto II in 983. Otto III also sought to reestablish Imperial control over the city of Rome, which had revolted under the leadership of Crescentius II, and through it the papacy. Crowned as emperor, Otto III put down the Roman rebellion and installed his cousin as Pope Gregory V, the first Pope of German descent. After the Emperor had pardoned him and left the city, Crescentius II again rebelled, deposing Gregory V and installing John XVI as Pope. Otto III returned to the city in 998, reinstalled Gregory V, and executed both Crescentius II and John XVI. When Gregory V died in 999, Otto III installed Sylvester II as the new pope. Otto III's actions throughout his life further strengthened imperial control over the Catholic Church.