Also known as the Western Schism or the Great Western Schism, period from 1377 to 1417.
In 1377, Pope Gregory XI returned the papacy to Rome after it had been located in Avignon, France for 70 years, and died shortly afterwards. The relocated college of cardinals elected the new pope Urban VI. Because of Urban's intentions of asserting the supreme power of the Pope over the council, and his mental illness, the cardinals quickly elected a second pope, Clement VII, to replace him. Urban refused to resign and excommunicated Clement. Clement situated himself in Avignon and took on the title of "antipope". Thus dual, contradicting papacies were established in Rome and Avignon, leading to the further degradation of the power of the church. In order to end the schism, the (invalid) Council of Pisa elected Alexander V to replace the two popes; but because neither pope agreed to resign, this had the effect of creating a 3rd papacy which only led to even more confusion and anarchy. Finally, in 1417 the Council of Constance, among other things, elected pope Martin V. After the consented resignation of the existing popes, Martin went to work reestablishing the power and land of the Roman papacy.