On the 18th May 1291, the Crusader-controlled city of Acre was seized by the Muslim forces of the Mamluk Sultan Al-Ashraf Khalil. The Siege of Acre, sometimes known as the Fall of Acre, marked the last attempt to exert Crusader influence in the Holy Land.
Acre had been under Christian control since it was besieged in 1191 during the Third Crusade, and had quickly become the capital of the Kingdom of Jerusalem. With the rise of the Mamluk Sultanate in nearby Egypt in 1250, Crusader holdings became targets for conquest.
The spark for the attack on Acre was the suspected killing of a Muslim for an affair with the wife of a Christian. This coincided with the arrival of over 1,600 poorly disciplined Italian reinforcements for the city, who allegedly pillaged nearby towns for supplies and killed a number of Muslims in the process.
These killings were cited by the Mamluks as reason to cancel a ten-year truce they had signed with the Crusaders. Having amassed an army of many thousands, Sultan Khalil therefore began the siege on 5th April and within less than a month his forces had reached the city walls and begun to mine out the base of the walls and defensive towers. These began to collapse on the 8th May, and a few days later the full infantry attack on the city began. By nightfall on 18th May the Christians had been defeated, their leaders having either fled by boat or been killed in the fighting.