Elected near the end of 827; died January, 844. When Gregory was born is not known, but he was a Roman and the son of John. Before his election to the papacy he was the Cardinal-Priest of the Basilica of St. Mark, which he adorned with mosaics yet visible. For his piety and learning he was ordained priest by Paschal I. This man, of distinguished appearance and high birth, was raised to the chair of Peter, despite his protestations of unfitness, mainly buy the instrumentality of the secular nobility of Rome who were then securing a preponderating influence in papal elections. But the representatives in Rome of the Emperor Louis the Pious would not allow him to be consecrated until his election had been approved by their master. This interference caused such delay that it was not, seemingly, till about March, 828, that he began to govern the Church.

Throughout the greater part of his pontificate Gregory was involved in the quarrels between Louis and his sons which were to prove fatal to the domination of the Franks. Owing perhaps to a want of political insight or to an over-sympathetic or sanguine temperament, or, it may be, to a want of firmness of character, his efforts to promote domestic peace in the imperial family were not attended either with success or with glory. By a solemn deed, confirmed by Paschal I, Louis had made a division of the empire in favour of the three sons of his first wife, Lothair I, Pepin, and Louis the German (817). But on her death, he married the young and ambitious Judith, and was soon induced by her to devote himself wholly to furthering the interests of their son, afterwards known as Charles the Bald. Charles's half-brothers combined in arms against their father (830), seized and imprisoned him, and compelled him to confirm the Constitution of 817. The brothers, however, soon disagreed among themselves and Louis was restored to power by a diet at Nimwegen, and, by a decision of the pope, to his wife from whom he had been separated by force (Oct., 830). Untaught by experience, Louis continued his policy of favouring his youngest son. The brothers again flew to arms, and the eldest, Lothair (who was ruling Italy), by argument, by deception, and perhaps by gentle pressure, induced Gregory to accompany him across the Alps. The appearance of the pope in the camp of the rebels made it appear that he was in their favour. Hence the bishops who remained faithful to the emperor, suspicious of the pope's good faith, would not come to him when he summoned them to his presence. It was to no purpose that Gregory repelled their accusations. When at length he met Louis himself, he found that Louis also did not trust him. While these negotiations were in progress, Lothair, who was false to everyone, was suborning the allegiance of his father's soldiers. Betrayed in consequence, Louis once again fell into the hands of his sons. Lothair seized the empire, allowed Gregory to return to Rome a sadder and a wiser man, and degraded his father (833). But next year witnessed a second fraternal quarrel, and a second restoration of Louis, who was weak enough to allow Lothair to retain the Kingdom of Italy. The result of his mistaken acts of clemency was not only that he had to protect the pope against Lothair's aggressions but that he had to face another rebellion of one of his sons. In marching to put it down, he died (June, 840).

His death put Lothair in possession of the imperial name. To be emperor in fact, he resolved to crush his brothers by force of arms. Detaining the legate whom Gregory dispatched to try and make peace, Lothair crossed the Alps. The terrible battle of Fontenay (now Fontenoy- en-Puisaye) near Auxerre (841), resulted not only in the defeat of Lothair, but in the practical annihilation of the Frankish people, and in the end of their empire. While the empire was collapsing, the Saracens were pushing forward their conquests. During Gregory's pontificate they possessed themselves of Sicily, and had been invited into Italy to take part in the wars of the petty princes of South Italy. To do what he could for the safety of Rome, the pope fortified the ancient Ostia by the erection of a stronghold called after himself Gregoriopolis. Equally for the benefit of Rome and the "Patrimony of St. Peter", Gregory repaired aqueducts and churches and founded "farm colonies" in the Campagna. He seconded the heroic efforts which St. Anaschar, the Apostle of the North, was making for the conversion of Sweden, authorizing his consecration as the first Archbishop of Hamburg, sending him the pallium, and "before the body and confession of Blessed Peter", giving him "full authority to preach the Gospel" and making him his legate "among the Swedes, Danes and Slavs."

Gregory gave the pallium to the Archbishops of Salzburg, Canterbury, and Grado, and favoured the latter against the encroachments of the Patriarch of Aquileia. He also supported Aldric, Bishop of Le Mans, who got into difficulties through his loyal support of Louis against his rebellious sons. To oblige Louis, Gregory caused some of his ecclesiastics to be trained in music in Rome, and he instructed him to proclaim the observance of the feast of All Saints throughout the empire. Gregory was buried in St. Peter's.

Liber Pontificalis, ed. DUCHESNE, II, 73 sqq; the Lives of Louis the Pious by THEGANUS in Mon. Germ. Hist.; Scriptores, II, and P.L., CVI, and by the ASTHONOMER in Mon. Germ. Hist.; Scriptores, II, and P.L., CIV; the Annals of EINHARD, etc.; the Historiae of NITHARD in P.L., CXV; the works of AGOBARD in P.L., CIV; and the Life of Wala by PASCHASIUS RADBERT in P.L., CXX; see HIMLY, Wala et Louis le Debonnaire; CHEVALLARD, St. Agobard; MANN, Lives of the Popes in the Early Middle Ages, II.

Horace K. Mann.