Otto III (June/July 980 – 23 January 1002) was Holy Roman Emperor from 996 until his death in 1002. A member of the Ottonian dynasty, Otto III was the only son of the Emperor Otto II and his wife Theophanu. Otto III was crowned as King of Germany in 983 at the age of three, shortly after his father's death in Southern Italy while campaigning against the Byzantine Empire and the Emirate of Sicily. Though the nominal ruler of Germany, Otto III's minor status ensured his various regents held power over the Empire. His cousin Henry II, Duke of Bavaria, initially claimed regency over the young king and attempted to seize the throne for himself in 984. When his rebellion failed to gain the support of Germany's aristocracy, Henry II was forced to abandon his claims to the throne and to allow Otto III's mother Theophanu to serve as regent until her death in 991. Otto III was then still a child, so his grandmother, Adelaide of Italy, served as regent until 994. 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. From the beginning of his reign, Otto III faced opposition from the Slavs along the eastern frontier. Following the death of his father in 983, the Slavs rebelled against imperial control, forcing the Empire to abandon its territories east of the Elbe river. Otto III fought to regain the Empire's lost territories throughout his reign with only limited success. While in the east, Otto III strengthened the Empire's relations with Poland, Bohemia, and