Summer – Adalbert II, margrave of Tuscany, revolts (pushed by his wife Bertha) against his cousin, Emperor Lambert II. The Tuscan army proceeds against the Lombard capital of Pavia. Lambert with his forces at Marengo defeats Adalbert at Borgo San Donnino, taking him, as a prisoner, to Pavia.
October 15 – Lambert II dies from falling off his horse while hunting — or is killed (possibly assassinated by supporters of Maginulf of Milan). After the death of Lambert, his rival Berengar I gains recognition as king of Italy. He releases Adalbert II and receives homage from the Italian nobles.
John IX holds councils at Rome and Ravenna to rehabilitate the late Pope Formosus. He condemns the Cadaver Synod of the late Pope Stephen VI, and restores the clergymen who were deposed by Stephen's faction.
^Michel Parisse, "Lotharingia", The New Cambridge Medieval History, III: c. 900–c. 1024, ed. Timothy Reuter (Cambridge: Cambridge University Press, 2005), pp. 313–15.