The bloodless Crusade of Frederick II, a diplomatic skirmish that was one episode in the rivalry of the Ayyubid princes who were al-‘Adil’s heirs, has left interesting traces in the Muslim histories of the epoch. Here the main sources are Sibt ibn al-Jauzi, himself a witness of and participant in the Muslim reaction to the surrendering of Jerusalem to the Hohenstaufen, and Ibn Wasil, who did not know Frederick personally, but was later ambassador to Manfred in southern Italy and has left personal and lively, if not always accurate, details of the Hohenstaufen’s phil-Islāmic tendencies. The impressions of those who were close to the Emperor during his visit to Jerusalem and saw his pro-Islāmic bias in political matters and his religious scepticism and scorn would, if they had been known in Europe, have received a warm welcome as support for the Vatican-inspired anti-Frederick polemic then current. A comprehensive example of this is to be found among Frederick’s diplomatic correspondence, in two letters in Arabic sent by him, shortly after his return to Italy, to a friend of his, an amir at the Ayyubid court. These have been preserved for us by an unknown eastern chronicler. Beneath the Arabic rhetoric, certainly the work of an Arab secretary, concrete historical references reveal the awareness of his imperial dignity and the fierce animosity to the Pope that are so clearly to be seen in the rest of his public utterances.

In 625/1228 the Emperor Frederick arrived in Acre with a great company of Germans and other Franks. We have already described how the amīr Fakhr ad-Din, the son of the Shaikh ash-Shuyūkh, was sent to the King-Emperor from. the Sultan al-Malik al-Kamil. This was in the time of al-Malik al-Mu‘azzam.1 The idea of the approaches made to the Emperor, the King of the Franks, and of his invitation, was to create difficulties for al-Malik al-Mu‘azzam and prevent his availing himself of the help offered to him by the Sultan Jalāl ad-Din ibn ‘Alā’ ad-Din Khwarizmshāh and Muzaffar ad-Din of Arbela, in his quarrel with al-Kamil and al-Malik al-Ashraf.