Empress Theophanu, to devise a plan to depose the newly installed Pope Gregory V. In 997, with the active support of Byzantine Emperor Basil II, Crescentius II led a revolt against Gregory V, deposed him, and installed John Philagathos as Pope John XVI, an antipope, in April 997. Gregory fled to Pavia in northern Italy, held a synod, and excommunicated John. The new bishop of Piacenza, Siegfried, came north to meet Otto at Eschwege in July. Otto detached the city from the county of Piacenza and granted it to the bishop in perpetuity. Putting down the Slavic forces in eastern Saxony, Otto III began his second expedition into Italy in December 997. Accompanied by his sister Sophia into Italy, Otto III named his aunt Matilda, Abbess of Quedlinburg, as his regent in Germany, becoming the first non-duke or bishop to serve in that capacity. Otto III peacefully retook Rome in February 998 when the Roman aristocracy agreed to a peace settlement. With Otto III in control of the city, Gregory V was reinstated as pope. John XVI fled, but the Emperor's troops pursued and captured him, cut off his nose and ears, cut out his tongue, broke his fingers, blinded him, and then brought him before Otto III and Gregory V for judgement. At the intercession of Saint Nilus the Younger, one of his countrymen, Otto III spared John XVI's life and sent him to a monastery in Germany, where he would die in 1001. Crescentius II retreated again to the Tomb of Hadrian, the traditional stronghold of the Crescentii, and was then besieged by Otto III's imperial army. Towards the end of April, the stronghold was breached, and Crescentius II was taken prisoner and executed by decapitation. His body was put on public display at Monte Mario. Reign from Rome Otto III made Rome the administrative capital of his Empire and revived elaborate Roman customs and Byzantine court ceremonies. During his time in Italy, the Emperor and the Pope attempted to reform the Church, and confiscated church property was returned to the respective religious institutions. Additionally, after the death of the Bishop of Halberstadt in November 996, who had been one of the masterminds behind the abolition of the bishopric of Merseburg, Otto III and Pope Gregory V began the process of reviving the Diocese. Otto I had established the Diocese in 968 following his victory over the Hungarians