to Venice as Doge in 977, restoring the city's friendly relationship with the Empire. However, Vitale's reign was short (less than two years) and he too voluntarily abdicated to become a monk. With the position vacant, the pro-Byzantine Tribuno Memmo became the new Doge in 979. With the change in leadership, Otto II was reluctant to renew the city's commercial agreements which his father had previously granted to the city. It was only after the intervention of Otto II's mother, the dowager empress Adelaide of Italy, that the Emperor renewed the agreements. Violence erupted in Venice during 980 due to tensions between the pro-Ottonian Coloprini family and the pro-Byzantine Morosini family. The Coloprini pleaded with the Emperor for support. Seeing an opportunity to fully incorporate Venice into the Empire, Otto II agreed. Upon arriving in Italy in 981, Otto II immediately imposed a trade embargo against the island republic. When the initial embargo showed little effect on Venice, Otto II imposed a second embargo in 983 which dealt considerable damage to the Venetian economy. The effects were disastrous enough to cause the ruling Venetian families to surrender to Otto II, but Otto II's untimely death that year prevented him from capitalizing on his victory. Religious policy Otto II followed the policy of his father in expanding the importance of the Church in his Empire, in particular the importance of monasticism and monasteries. The Church and its organs served as a supporting and stabilizing factor in the Empire's structure. To fulfill these tasks, Otto II strengthened the legal integrity and economic independence of the bishops from the secular nobility. The Ottonians had a particular religious interest in Memleben as both Otto II's father Otto I and grandfather Henry I had died there. Otto II and his wife Theophanu enhanced the spiritual importance of the city by establishing a Benedictine Imperial abbey there: the Memleben Abbey. Within a short time, the Memleben Abbey had become one of the richest and most influential of the Imperial abbeys. These measures and the unusual size of the abbey perhaps suggest that Memleben may have been intended as an Imperial Mausoleum for the Ottonians. Following the suppression of Henry II's rebellion, Otto II used the Empire's monasteries as the location for the treason trials. While his father had founded only one monastery (Otto I later replaced the abbey with the Cathedral of Magdeburg) during his 37-year