of
San Pietro in Vincoli. This is one of the oldest parts of the church and would have looked similar in the 11th century to how it looks today. Anselmo had the support of his friend Cardinal Hildebrand, a driving force behind the promulgation of
In Nomine Domini and the future
Pope Gregory VII,
Godfrey III, Duke of Lower Lorraine, Although Anselmo was well-known and respected within the German court, the assent of the
Holy Roman Emperor to the election was not sought. Displeased with the new process, a group of
Roman nobles and
Lombard bishops, let by Guibert, the royal chancellor of Italy, beseeched
Agnes de Poitou, empress-regent of
Henry IV, Holy Roman Emperor, to nominate Bishop Pietro Cadalo to succeed Nicholas II. Cadalo was elected
Antipope Honorius II at a
synod convoked at
Basel on 28 October 1061, at which no cardinals were present. Antipope Honorius II proceeded to march on Rome, defeating Alexander II and taking control of St. Peter's Basilica and its environs on 14 April 1062. The intervention of Godfrey III convinced Honorius II and Alexander II to retire to Parma and Lucca respectively, awaiting mediation between Godfrey III and the Imperial court. However,
Anno II, Archbishop of Cologne had engineered a ''
coup d'état'' against the empress regent. As regent, Anno convened the
Council of Augsburg (October 1062) and sent
Burchard II, Bishop of Halberstadt as an envoy to Rome. Burchard cleared Alexander II of charges of
simony and recognized him as the new pontiff. Alexander II
excommunicated Honorius II in 1063, but after a counter-synod Honorius II was able to establish himself in
Castel Sant'Angelo and wage war against Alexander II for another year before fleeing again to
Parma. The
Synod of Mantua (
Pentecost, 31 May 1064)
anathematized Cadalo and declared Alexander II the rightful pope. ==Cardinal electors==