In September, Arnulf supported an attempt to place his uncle Charles, Duke of Lower Lorraine, on the French throne.
[citation needed] In June 991 Archbishop Seguin of Sens presided over a Council of Reims in the Basilica of Saint Basle, which deposed Arnulf for alleged high treason, in favour of Gerbert.
Pope John XV sent Leo, abbot of Saints Boniface and Alexius at Rome, as legate to preside over a synod at Mouzon on 2 June 995.
A second synod, held on 1 July, declared the whole process of deposition and elevation to be illegal and invalid.
He held the see until his death in 1021, then the only direct male line descendant of the Carolingian family in the eldest living branch aside from his first cousin Louis, who died two years later.