Queen Sybil of Jerusalem, queen in her own right, was ruler of the kingdom of Jerusalem from 1186 to 1190. Her reign saw the loss of the city of Jerusalem to Saladin, and the beginning of the Third Crusade. Her reign began with her nobles divided and crisis looming; by her death the military forces of Christian Europe were uniting with her and her husband, intent on recovering what had been lost. Sybil died before the bulk of the forces of the Third Crusade could arrive in the kingdom, and Jerusalem was never recovered. But although Sybil failed, she went down fighting – spiritually, even if not physically. This study traces Sybil’s life, from her childhood as the daughter of the heir to the throne of Jerusalem to her death in the crusading force outside the city of Acre. It sets her career alongside that of other European queens and noblewomen of the twelfth century who wielded or attempted to wield power and ask how far the eventual survival of the kingdom of Jerusalem in 1192 was due to Sybil’s leadership in 1187 and her determination never to give up.