Saint Francis went on the Fifth Crusade in 1219. He was shocked at what he saw in the Crusaders' attitude after the conquest of Damietta in Egypt. He and a single companion decided to go to the Muslim leader of Palestine, Syria, and Egypt: Al-Malik al-Kamil. The War was a bloody affair and Francis helped to bring peace. His companion was Illuminatus who had a knowledge of Arabic. Al-Malik al-Kamil welcomed Francis and Illuminatus. He was the nephew of Saladin and was a devout man. He decided to spare the life of Saint Francis. He sensed in him a true holy man who was prepared to sacrifice himself to bring peace. The gifts he gave Saint Francis can still be seen in Assisi today. Francis was allowed to visit the holy sites in the Holy Land.
We know this story from the Christian side. Is there any reference to this meeting from the Muslim side? Louise Massignon (+1962) was a Catholic scholar of Islam and a pioneer of Christian-Muslim understanding. He went through the Arabic sources. According to Ibn al-Zoggats Kavakib, there was a record of al-Kamil's spiritual counselor having a memorable meeting with a Christian male (rahib). Massignon thinks this refers to Saint Francis.
Massignon himself' experienced kindness from his Muslim friends. There was tension between France and the Ottoman Empire before World War I. He was arrested as a spy and his life was in danger. His Muslim friends pleaded on his behalf. In so doing they were putting their own lives in danger. Massignon was released. Up to this, he had been an atheist but he converted to Catholicism but with huge respect for Islam. He spends his life bringing peace and understanding between the two faiths.
The fighting between the Crusaders and the Sultan's forces was marked by bloodshed and cruelty. The Crusaders marched on Cairo, but Al-Kamil opened the dams and allowed the Nile to flood. The Crusaders were, literally, bogged down and at the mercy of Al-Kamil. However, the Sultan asked the Crusaders to lay down their weapons. He accepted their weapons and gave them safe passage to the port. This story is different from so many other stories from the Crusades. This was very much in the spirit of Saint Francis and it is tempting to believe that Saint Francis influenced Al-Kamil. We do not have enough evidence to know if this was the case. Al-Kamil was very impressed with the holy man, Saint Francis. He admired Saint Francis and his self-giving.