Pope Celestine II was the head of the Roman Catholic Church from 1143 to 1144. Born as Guido di Castello, he was elected pope during a time of political turmoil in Italy. His papacy was marked by efforts to mediate conflicts between the Holy Roman Empire and various Italian city-states. Celestine II's reign was short-lived, lasting only about a year before his death in 1144. He is remembered for his attempts to promote peace and unity within the Church and for his support of the Second Crusade, which aimed to reclaim the Holy Land from Muslim control.