This is a biography of Frederick II (1194-1250), King of Sicily, Holy Roman Emperor, King of Jerusalem, concentrating on the complete history of his kingdoms and placing his reign in a wide context. David Abulafia presents Frederick as less tolerant, less far-sighted in his cultural interests and less ambitious to break the power of the Roman Church than has previously been thought. Until now too, the success of Frederick's enemies in denigrating him has grossly distorted the understanding of his reign and its effects, but David Abulafia aims to redress the balance, presenting the man as a traditionalist and a deluded optimist searching for peace with two aggressive and suspicious popes.