The Battle of Ascalon took place on 12 August 1099 shortly after the capture of Jerusalem, and is often considered the last action of the First Crusade. The crusader army led by Godfrey of Bouillon defeated and drove off a Fatimid army, securing the safety of Jerusalem.

The siege of Jerusalem marked the successful end of the First Crusade, whose objective was the recovery of the city of Jerusalem and the Church of the Holy Sepulchre from Islamic control. The five-week siege began on 7 June 1099 and was carried out by the Christian forces of Western Europe mobilized by Pope Urban II after the Council of Clermont in 1095. The city had been out of Christian control since the Muslim conquest of the Levant in 637 and had been held for a century first by the Seljuk Turks and later by the Egyptian Fatimids. One of the root causes of the Crusades was the hindering of Christian pilgrimages to the Holy Land which began in the 4th century. A number of eyewitness accounts of the battle were recorded, including in the anonymous chronicle Gesta Francorum.