Pope John XVIII has occupied his time with details of ecclesiastical administration, authorizing a new see at Bamberg to serve as a base for missionary activity among the Slavs, a concern of Henry II's, and adjudicating a squabble between the abbot of Fleury and the bishops of Sens and Orléans.

During his whole pontificate he has allegedly been subordinate to the Crescentii clan leader who controls Rome.

The period is disturbed by the conflicts between the Ottonian Emperor and Arduin of Ivrea, who has styled himself King of Italy.

Rome is wracked with bouts of plague, and Saracens operating freely out of Sardinia ravage the Tyrrhenian coasts.

Ultimately he abdicates and, according to one catalog of Popes, retires to a monastery, where he dies shortly afterwards.

His successor, Pietro Boccapecora, the son of a shoemaker, had risen quickly through the church ranks to become Bishop of Albano in 1004; he assumes the regnal name of Sergius IV.