JOHN VIII., pope from 872 to 882, successor of Adrian II., was a Roman by birth. He defended the Roman State and the authority of the Holy See at Rome from the Saracens, and from the nascent feudalism which was represented outside by the dukes of Spoleto and the marquises of Tuscany and within by a party of Roman nobles. He agreed in 875 to bestow the imperial crown on Charles the Bald. About the time of the death of Charles he was compelled to come to terms with the Saracens, who were only prevented from entering Rome by the promise of an annual tribute. Carloman, the opponent of Charles's son Louis, then invaded northern Italy, and demanded the imperial crown.
John attempted to temporize, but Lambert, duke of Spoleto, a partisan of Carloman, whom sickness had recalled to Germany, entered Rome in 878 with an overwhelming force, and for 3o days virtually held John a prisoner in St. Peter's. Lambert, how ever, won no concession from the pope, who after his withdrawal went to France. There he presided at the council of Troyes, which
excommunicated the supporters of Carloman—amongst others Adalbert of Tuscany, Lambert of Spoleto, and Formosus, bishop of Porto, who was afterwards elevated to the papal chair. In 879 John returned to Italy accompanied by Boso, duke of Provence, whom he adopted as his son. He was compelled to promise his sanction to the claims of Charles the Fat, who received from him the imperial crown in 881. In order to secure the aid of the Greek emperor against the Saracens, he had already agreed to sanction the restoration of Photius to the see of Constantinople, and had withdrawn his consent on finding that he gained nothing from the concession. Charles the Fat gave him also no effectual aid. According to the annalist of Fulda, he was murdered (Dec. 16, 882) by members of his household. His successor was Marinus.