Pope Clement IV

Born Gui Foucois around 1190, he climbed through the Church ranks as Bishop of Le Puy in 1257, Archbishop of Narbonne two years later, then Cardinal of Sabina in 1261. His papal election in 1265 came after a four-month conclave at Perugia, where cardinals fought over whether to summon Charles I of Anjou - Louis IX's youngest brother - to continue the fight against the Hohenstaufens. Once enthroned, Clement IV became an unlikely sponsor of intellectual revolution: he encouraged Roger Bacon to complete the Opus Majus, a landmark work on optics and scientific method, while also supporting Thomas Aquinas. He died in office on 29 November 1268, having spent his papacy balancing warfare and scholarship.