Pope Leo VIII was installed as Pope on December 4, 963, by Holy Roman Emperor Otto I, after the Emperor removed John XII for conspiring against him. Leo Initially a layman (a papal notary) was hurriedly ordained and made a Bishop in a single day to fill the seat, making his legitimacy disputed during the turbulent period of 963–965.
When Otto I left Rome in 964, John XII returned, deposed Leo, and forced him to flee. John II died suddenly and the Romans elected Benedict V as the new Pope. Otto I returned, forced the deposition of Benedict V, and reinstated Leo VIII, who reigned from June 23, 964, until his death on March 1, 965.Because John XII was still alive and contested his removal, Leo is considered an antipope for the first part of his reign. Leo VIII is known for granting the emperor strong privileges over the Papal States. However, his second term is recognized in the official Vatican chronology, despite the chaotic circumstances.