Pope from 1431 to 1447, during the final stage of a serious challenge to papal absolutism by supporters of the theory of Conciliarism. Born as Gabriele Condulmer at Venice about 1383, he pursued a career at the papal curia after his uncle Angelo Correr became a cardinal and then was elected pope as Gregory XII (1406-1415). Gabriele became bishop of Siena in 1407 and a cardinal the following year. He never studied at a university and showed little interest in the new humanist culture. At his election, he promised to lead the reform of the church "in head and members" and to continue the church council that had already begun its sessions at Basel.
Eugenius attempted to dissolve the Council of Basel at the end of 1431, but the repudiation of this action not only by the council itself but also by most of the major European rulers forced him to back down. His relations with the council remained troubled. He refused to accept conciliar decrees declaring the supremacy of a council over all other authorities in the church and empowering a council to enact reforms without papal approval. In the papal bull Doctoris gentium (1437) he reasserted the papacy's claim to unlimited monarchical power over the church and ordered the council's sessions transferred to Ferrara in Italy. The great majority of the council rejected this order and in June 1439 formally declared Eugenius deposed. The pope's hand was strengthened by the agreement of the Greek Orthodox leaders to attend the council at Ferrara in order to reunify the eastern and western churches. The union proclaimed in 1439 ultimately fell through, but this apparent success helped Eugenius win the support of most of the major European rulers, especially since the decree of deposition and the election of a rival pope by the council made the council seem responsible for a new schism.
Eugenius solidified his power by negotiating a series of concordats (treaties) with individual governments, granting broad control of church appointments to the secular rulers in return for recognition of papal supremacy. Official support for the Council of Basel dwindled, though great numbers of clergy in northern Europe, especially the educated ones, continued to support the principles of Conciliarism. Eugenius also faced great difficulty in maintaining control of the city of Rome, where some of the local nobility in 1434 staged a coup d'etat that forced the pope to flee to Florence, disguised as a monk. He did not return to Rome until 1443, an exile of nine years, two-thirds of which were spent in Florence.
Historical Dictionary of Renaissance. Charles G. Nauert. 2004.