Pope (1254-1261). Born around 1180, Rainald of Segni was elected pope on 12 December 1254, taking the name Alexander.
Throughout his pontificate Alexander largely continued the policies of his predecessors Gregory IX and Innocent IV, including crusades against the Staufen dynasty, the Moors in North Africa, and pagans in Finland and the Baltic region. By granting the rulership of Sicily to Edmund, son of King Henry III of England (1255), he persuaded Henry to commute his crusading vow to a campaign against Manfred, son of the emperor Frederick II, who was attempting to gain control of the kingdom. However, papal armies’ campaigns against Manfred were largely unsuccessful, while another initially promising crusade against the pro-Staufen Ezzelino of Romano and Oberto Pallavicini merely resulted in Pallavicini’s elimination of his rival Ezzelino. Alexander also engaged in negotiations with Theodore II Laskaris, the Greek emperor of Nicaea, regarding the potential surrender of Latin-held Constantinople and restoration of the Greek Orthodox patriarchate there in return for acknowledgment of papal supremacy in doctrinal matters and the reunion of the Greek and Latin churches. However, after Theodore died in 1258, his successor Michael VIII Palaiologos took Constantinople by storm shortly after Alexander’s decease.
As a cardinal, Alexander had witnessed the Mongols’ first incursions into eastern Europe and the missions sent by Innocent IV and Louis IX of France, which returned with letters calling for universal submission. During Alexander’s pontificate, the Mongol army of Hülegü invaded Syria, forcing the submission of the princes of Antioch and Cilicia, and Alexander’s attempts to forge a league to guard the eastern border of Christendom failed to prevent the Mongols’ invasion of Poland and Lithuania. His calls for crusaders to aid both eastern Europe (1253-1254, 1259) and Outremer(1260-1261) led to the departure of minor contingents, but the pope’s death prevented the materialization of a general passage, as well as of a council he had convoked to address threats to the Holy Land, Constantinople, Sicily, and eastern Europe.