After Arnulf returned to Germany and until his death, Lambert and his supporters, most powerful in the northeast and the centre of the peninsula, were in complete control of Italy. He retook Pavia and decapitated
Maginfred I of Milan, who had joined Arnulf. In October and November, he met Berengar outside of Pavia and the two reached an agreement whereby they parcelled the kingdom out between them, Berengar keeping the realm between the
Adda and the Po and Lambert the rest. They shared
Bergamo. This was a confirmation of the
status quo of 889. Lambert also pledged to marry Gisela, Berengar's daughter. It was this partitioning which caused the later chronicler
Liutprand of Cremona to remark that the Italians always suffered under two monarchs. In early 897, Lambert journeyed to Rome with Ageltrude and Guy to receive reconfirmation of his imperial title. The vengeful Lambert and Ageltrude also persuaded
Pope Stephen VI, elected by their influence, to put the corpse of Formosus on trial for various crimes. The body, stripped of its papal robes and mutilated, was thrown into the river
Tiber after the "
Cadaver Synod." In January 898,
Pope John IX rehabilitated Formosus against their will. Lambert convened a diet at Ravenna in February. Seventy bishops met and confirmed the pact of 891, the invalidity of Arnulf's coronation, and the validity of Lambert's imperial title. They legitimised the election of John IX. They also solved the Formosan question and confirmed his rehabilitation. Most significantly for Lambert, however, they reaffirmed the
Constitutio Romana of
Lothair I (824), which required the imperial presence at papal elections. ==Battle of Marengo==