Pope Clement IV (; 23 November 1190 – 29 November 1268), born Gui Foucois (; or ) and also known as Guy le Gros (French for "Guy the Fat"; ), was bishop of Le Puy (1257–1260), archbishop of Narbonne (1259–1261), cardinal of Sabina (1261–1265), and head of the Catholic Church from 5 February 1265 until his death. His election as pope occurred at a conclave held at Perugia that lasted four months while cardinals argued over whether to call in Charles I of Anjou, the youngest brother of Louis IX of France, to carry on the papal war against the Hohenstaufens. Pope Clement was a patron of Thomas Aquinas and of Roger Bacon, encouraging Bacon in the writing of his Opus Majus, which included important treatises on optics and the scientific method. Early life Clement was born in Saint-Gilles-du-Gard in the Languedoc region of France, to a successful lawyer, Pierre Foucois, and his wife Marguerite Ruffi. At the age of nineteen, he enrolled as a soldier to fight the Moors in Spain. He then pursued the study of law in Toulouse, Bourges and Orleans, becoming a noted advocate in Paris. In the latter capacity he acted as secretary to King Louis IX, to whose influence he was chiefly indebted for his elevation to the cardinalate. He married the daughter of Simon de Malbois and had two daughters. Upon the death of his wife, he followed his father's example and gave up secular life for the Church. His rise was rapid. Ordained in the abbey of Saint-Magloire, Paris, he became pastor of Saint-Gilles in 1255. In 1257, he was appointed Bishop of Le Puy; in 1259, he was appointed Archbishop of Narbonne; and in December 1261, he became the first cardinal created by Pope Urban IV, for the See of Sabina. He was the papal legate in England between 1262 and 1264. He was named a cardinal (grand penitentiary) in 1263. Pontificate In this period, the See of Rome was engaged in a conflict with Manfred, King of Sicily, the illegitimate son and designated heir of Holy Roman Emperor Frederick II of Hohenstaufen, but whom papal loyalists, the Guelfs, called "the usurper of Naples". Clement IV, who was in France at the time of his election, was compelled to enter Italy in disguise. He immediately took steps to ally himself with Charles of Anjou, his erstwhile patron's brother and the impecunious