He was born in Gemra, Anagni (Italy); Reinaldo Agnani, count of Segni, was called and was cardenal-obispo of Ostia. He entered the Franciscan order. It was Pope from 1254 to 1261, as the successor of Pope Innocent IV, with the number 183. He excommunicated Manfred, usurper of the throne of Naples, and pursued the party town, all of which cause a series of wars. Supported Juan sin Tierra in its claims to the throne of England; opposed to Alfonso X of Castile was Emperor of Germany, and at the request of san Luis authorized the Inquisition in France. He granted privileges to the University of Salamanca and ordered that the elected bishops consagrasen is within six months. Continued the antisuaba policy, not to obstruct access to Sicily. It restored the privileges of the Dominican order, that innocent IV had cut at the beginning of his pontificate. Brought together in a single body five congregations of hermits, two of San Guillermo, and three of San Agustín. In his time, the sect of the Flagellants appeared in Italy. He died in Vieterbo may 25, 1261. It succeeded him to the throne of Urban IV.