As Crusaders went, they loathed Islam and kept to their Frankish ways during their 200-year reign in the Holy Land.But one ruler stood out for his benevolent treatment of Muslims and affinity for Islamic civilization. Frederick II, leader of the Sixth Crusade of 1228-1229, was fluent in Arabic, conquered Jerusalem without a fight, fortified Jaffa and left what turned out to be the only Crusader inscription in the Arabic language ever uncovered.“We don’t have anything like this ever found in the Middle East,” Prof. Moshe Sharon, a calligrapher who deciphered the inscription, told The Media Line. “No other crusader ruler left anything in the Arabic language.”The unique 800-year-old archaeological discovery had been found in a wall of a building in Tel Aviv, probably affixed there years ago. The gray marble slab was taken for examination by Prof. Sharon and Ami Shrager of Hebrew University of Jerusalem who released their findings on Monday.It bears the name Frederick II, the date 1229 and his titles including “King of Jerusalem.” A small part in Latin survived, but not enough to read. Sharon is certain the slab was attached to the walls of the citadel the ruler built in Jaffa, but was tossed aside over the years following its destruction until it was used in the current building.But more important than the marble slab is the information it reveals about this unusual Crusader ruler. A native of Sicily, he was probably one of the only Crusader rulers who was fluent in Arabic and he also was deeply aware of the Islamic world’s advances.“This was a great find because we don’t have such a ruler who knew Arabic and he was very much interested in Islam and his court was full of Muslim scientists and ambassadors, so he is a very special character,” Sharon said.Frederick II was so non-belligerent that he was able to befriend the Egyptian sultan Al-Malik Al-Kamil and win an armistice from him that made him ruler over Jerusalem without a fight.“He was breaking the norm in many things. He was interested in science and excommunicated by Pope Gregory IX and crowned himself king of Jerusalem. He was a character,” Sharon said.