He was made cardinal by Pope Honorius II in 1124 and papal chancellor by Pope Innocent II, whom he aided against the antipope Anacletus II. He was elected to succeed Celestine II on March 12, 1144. When King Roger II of Sicily invaded papal lands and forced Lucius to accept his truce, Anacletus' brother, the patrician Giordano Pierleoni, led the Romans to proclaim a constitutional republic free from papal civil rule. Lucius opposed this bid for Roman independence, led an unsuccessful assault against the rebels, and presumably died from injuries suffered in the conflict.