Al - Kamil Al - Kamil ( ) ( full name : al - Malik al - Kamel Naser al - Din Abu al - Ma ' ali Muhammed ) ( 1180 – 1238 ) was a Kurdish ruler , the fourth Ayyubid sultan of Egypt . During his tenure as sultan , the Ayyubids defeated two crusade s . In a temporary agreement with the Crusaders , he ceded Jerusalem to the Christians and is known to have met with Saint Francis of Assisi at the alleged " Trial by Fire " . Biography . Jazira Campaign . Al - Kamil was the son of sultan al - Adil ( " Saphadin " ) , a brother of Saladin . Al - Kamil ' s father was laying siege to the city of Mardin in 1199 when he was called away urgently to deal with a security threat in Damascus . Al - Adil left al - Kamil to command the forces around Mardin continuing the siege . Taking advantage of the Sultan ' s absence , the combined forces of Mosul , Sinjar and Jazirat ibn Umar appeared at Mardin when it was on the point of surrender , and drew Al - Kamil into battle . He was badly defeated and retreated to Mayyafariqin . However dissent and weakness among his opponents meant that Al - Kamil was able to secure Ayyubid rule in the Jazira region by taking Harran . Viceroy of Egypt . In 596 / 1200 , after proclaiming himself Sultan , Al - Adil invited Al - Kamil to come from the Eastern Territories to join him in Egypt as his viceroy ( na ' ib ) in that country . Al - Adil ' s second son , Al - Muazzam Isa , had already been made prince of Damascus in 594 / 1198 . It appears that Al - Adil allowed Al - Kamil a fairly high degree of authority , since he oversaw much of the work on the Cairo citadel , issued decrees in his own name , and even managed to persuade his father to dismiss the powerful minister Ibn Shukr . Al - Kamil remained viceroy until his father ' s death in 1218 when he became Sultan himself . The Fifth Crusade . In 1218 when Al - Adil died , the Ayyubid domains were divided into three parts , with Al - Kamil ruling Egypt , his brother Al - Muazzam Isa ruling in Palestine and Transjordan , and a third brother , Al - Ashraf Musa in Syria and the Jazira . Nominally the other two recognised Al - Kamil ' s supremacy as Sultan . Unusually for an Ayyubid succession , there was no obvious dissent or rivalry between the brothers at this point , partly because just before Al - Adil ' s death , Egypt had been attacked by the forces of the Fifth Crusade . Al - Kamil took command of the forces which defended Damietta against the Crusaders . In 1219 he was almost overthrown by a conspiracy led by the amir Imad ad - Din ibn al - Mashtub , commander of the Hakkari Kurdish regiment , to replace him with his younger and more pliant brother al - Faiz Ibrahim . Alerted to the conspiracy , Al - Kamil had to flee the camp to safety and in the ensuing confusion the Crusaders were able to tighten their grip on Damietta . Al - Kamil considered fleeing to Yemen , which was ruled by his son Al - Mas ' ud , but the timely arrival of his brother Al - Muazzam from Syria with reinforcements brought the conspiracy to a swift end . Al - Kamil made many offers of peace to the Crusaders , all of which were rejected , due to the influence of the papal legate Pelagius . He offered to return Jerusalem and rebuild its walls ( which his brother had torn down earlier in the year ) , and to return the True Cross ( which he probably did not have ) . At one point he even negotiated with Francis of Assisi , who had accompanied the crusade , and who apparently tried to convert the sultan . Due to famine and disease after the Nile failed to flood , al - Kamil could not defend Damietta and it was captured in November 1219 . The sultan withdrew to al - Mansourah , a fortress further up the Nile . After this there was little action until 1221 , when al - Kamil offered peace again , proposing to surrender the entire territory of the Kingdom of Jerusalem , except Transjordan , in return for the Crusaders evacuating Egypt but was again refused . The Crusaders marched out towards Cairo , but al - Kamil simply opened the dams and allowed the Nile to flood , and finally the Crusaders accepted an eight - year peace . He retook Damietta in September . In the following years there was a power struggle with his brother al - Mu ' azzam , and al - Kamil was willing to accept a peace with emperor and King of Sicily Frederick II , who was planning the Sixth Crusade . Al - Mu ' azzam died in 1227 , eliminating the need for a peace , but Frederick had already arrived . After al - Mu ' azzam ' s death , al - Kamil and his other brother al - Ashraf negotiated the Treaty of Jaffa , giving all of Palestine ( including Transjordan ) to al - Kamil and Syria to al - Ashraf . In February 1229 al - Kamil negotiated a ten - year peace with Frederick II and returned Jerusalem and other holy sites to the Crusader kingdom . Power Struggle and the Treaty of 1229 . In the following years there was a power struggle with his brother al - Mu ' azzam , and al - Kamil was willing to accept a peace with emperor and King of Sicily Frederick II , who was planning the Sixth Crusade . Al - Mu ' azzam died in 1227 , eliminating the need for a peace , but Frederick had already arrived in Palestine . After al - Mu ' azzam ' s death , al - Kamil and his other brother al - Ashraf negotiated a treaty , giving all of Palestine ( including Transjordan ) to al - Kamil and Syria to al - Ashraf . In February 1229 al - Kamil negotiated a ten - year peace with Frederick II and returned Jerusalem and other holy sites to the Crusader kingdom . The treaty of 1229 is unique in the history of the Crusades . By diplomacy alone and without major military confrontation , Jerusalem , Bethlehem , and a corridor running to the sea were ceded to the kingdom of Jerusalem . Exception was made for the Temple area , the Dome of the Rock , and the Aqsa Mosque , which the Muslims retained . Moreover , all current Muslim residents of the city would retain their homes and property . They would also have their own city officials to administer a separate justice system and safeguard their religious interests . The walls of Jerusalem , which had already been destroyed , were not rebuilt , and the peace was to last for 10 years . However although there was peace with the Crusaders , al - Kamil had to contend with the Seljuks and the Khwarezmia ns before he died in 1238 . Successors . His sons as - Salih Ayyub and al - Adil II succeeded him in Syria and Egypt respectively , but the Ayyubid empire soon descended into civil war . In 1239 the treaty with Frederick expired , and Jerusalem came under Ayyubid control .