The Kingdom of Jerusalem, surrounded by enemies now faced inevitable defeat. Saladin could raise armies potentially numbering 100,000 or more with Syria and Egypt under his control. Nur ad-Din however was still alive until 1174 and Saladin's power in Egypt was seen as a rebellion against his vassalage to Nur ad-Din. After the latter's death Syria and Egypt remained united. A few Crusader victories, notably at Montgisard and a failed Ayyubid siege of Tiberias allowed the Crusaders to stave off defeat until 1187. By 1189 the Crusader realm had been diminished beyond all strength and relied increasingly on politically motivated and inexperienced western reinforcements.
However, after the fall of Jerusalem in 1187, the focus of the Crusaders shifted decisively towards Egypt and less so towards the Levant. This can be seen in the Third Crusade, where Richard the Lionheart recognized the importance of Egypt and twice suggested an invasion of the region. An assault against the Levant could not succeed without the resources and manpower of Egypt, which currently gave the Islamic powers in the region a decisive advantage. The Fourth, Fifth, Seventh, Eighth and Alexandrian Crusades all had Egypt as the intended target.
During the Fifth Crusade (1218-1221) a large force of Crusaders led by the papal legate Pelagio Galvani and John of Brienne took Damietta. The expeditionary force included French, German, Flemish and Austrian crusaders and a Frisian fleet. The army marched on Cairo but was cut off by flooding of the Nile and the campaign ended in disaster with Pelagio forced to surrender with what remained of his army.
During the Seventh Crusade King Louis IX of France invaded Egypt (1249-1250) and after occupying Damietta he marched towards Cairo. However the forces led by Robert I, Count of Artois were defeated at the Battle of Al Mansurah and then King Louis and his main army were defeated at the Battle of Fariskur where his entire army was either killed or captured. The king suffered the humiliation of having to pay an enormous ransom for his freedom.
The temporary victories were followed by defeats, evacuations or negotiations - ultimately amounting to nothing. By 1291, Acre, the last major Crusader fortress in the Holy Land fell to the forces of the Mamluk Sultan of Egypt, and any remaining territories on the mainland were lost over the next decade.