Fifth Crusade (1217-1221) - Since the Fourth Crusade never reached the Holy Land (or Egypt which was the intended target), a Fifth Crusade was required to accomplish the task.  Pope Innocent III had planned for another Crusade as early as 1208.  He issued the first papal bull calling for one in 1213, and followed it up with a second papal bull in 1215.  But he died in 1216 before an army was raised.  Part of the problem was that Western European nations had little appetite for another Crusade.  France, for one, was engaged in a sort of domestic crusade against the Cathars.  Emperor Frederick II was willing to assist, but was involved in a dispute with the Papacy, so the Pope barred him from joining.  The new Pope, Honorius III, turned to Central Europe and found willing participants in King Andrew II of Hungary and Duke Leopold VI of Austria.  Once again the Venetian fleet transported the army across the Mediterranean (this time with no strings attached).  In July 1218, an assault on the coastal Egyptian city of Damietta began.  The city was not captured, but a fortress nearby was at the end of August.  This at least allowed the Crusaders to establish a base in Egypt.  In the meantime, the army was reinforced by a coalition of Dutch, Flemish and Frisian knights led by Count William I of Holland.  Pope Honorius also sent over Pelagius of Albano to be the spiritual leader of the Crusade.  At one point, Francis of Assisi even joined the Crusade and was said to have preached to Sultan al-Kamil (without any effect).

Something rather uncharacteristic happened on the campaign.  The Crusaders formed an alliance with the Sultanate of Rûm (their original enemies in the First Crusade).  The Turks attacked the Arabs in the Levant in order to prevent the Ayyubids from redeploying troops to Egypt.  It ended up not making any difference.  The Crusaders finally began to march on Cairo in July 1221.  It was a disaster.  They traveled south along the Nile, which was no problem initially.  But with the end of summer came the rainy season and massive flooding.  The army got bogged down and many succumbed to insect borne diseases.  Their provisions were running out and they were forced to retreat.  Sultan al-Kamil sensed their vulnerability and launched a nighttime attack on the Crusader army.  Weakened by disease and hunger, it was badly beaten and forced to surrender.  The survivors were permitted to leave on condition that they withdrew from Egypt and an eight year treaty was signed between Papacy and the Ayyubid dynasty.