On 16 August, the Fatimids set fire to the siege tower, but the wind blew the flames back at the castle wall and caused part of it to collapse.

[2] Thereafter, the Fatimids were able to launch frequent raids into the kingdom from this fortress, and it also served as staging ground for larger Egyptian invasions of Jerusalem (such as in 1101, 1102, and 1105).

The Fatimid garrison in Ascalon received regular supplies from Egypt and was considered too strong for King Baldwin I of Jerusalem to attack it during the 1110s.

[9] Around 1149–1150, Baldwin III of Jerusalem rebuilt part of the fortifications of Gaza City, which at that point lay in ruins, 10 miles (16 km) south of Ascalon.

[13][14] Zengi's expansionism out of northern Syria around that time also led the emir of Damascus, Mujir ad-Din, to conclude an alliance with the Kingdom of Jerusalem in 1140 to protect his independence.

Mujir concluded an alliance with Nur in 1147, which contributed to the decision of the Crusaders to besiege Damascus in 1148, as the Kingdom of Jerusalem could be threatened by a unified Muslim force to its north and east.

Mujir continued to keep Damascus independent, and still cooperated with the Kingdom of Jerusalem on some occasions, though he and the city's population became more closely aligned with Nur.

In 1149 Nur defeated another Crusader state to the north of Jerusalem, the Principality of Antioch, and killed its ruler Prince Raymond at the Battle of Inab.

[21] Muslim sources noted a Crusader attack against the town of al-Farama in 1150, located on the edge of the Nile Delta, and in the following year the Fatimids launched naval raids against port cities in Palestine.

Their quarrel was eventually resolved and the kingdom reunited, though not before a Seljuk Turkish prince, Timurtash of Mardin, tried to take advantage of the civil war by attacking towards Jerusalem from Mujir ad-Din's territory.

The residents of the area fled for shelter inside the fortress,[23] and King Baldwin's army arrived outside the walls of Ascalon on 25 January 1153.

[10][19] He was accompanied by many important nobles and clergy of the kingdom:[24] Patriarch Fulcher, along with Raymond du Puy and Bernard de Tremelay, the Grand Masters of the Knights of the Hospital and of the Temple, respectively, and the secular leaders, including Hugh of Ibelin, Philip of Milly, Humphrey II of Toron, Maurice of Montreal, Walter of Saint-Omer, and Raynald of Châtillon.

[5] To the south of Ascalon in Gaza, scouts were posted throughout the area to warn in case reinforcements for the besieged fortress were sent from Egypt by land.

[28] William of Tyre wrote that the townspeople became involved with the response to the siege and that the number of defenders in Ascalon was twice the size of the attacking army.

[18] In response to the Crusader attack, the vizier Ibn al-Sallar began preparing reinforcements for the city in March, as well as a naval expedition.

[29] The Fatimid army set off and got as far as Bilbays, while Ibn al-Sallar supervised the final preparations of the fleet, including a naval review and the payment of the crews.

[27] However, a setback for Ascalon occurred on the night of 15-16 August when the besieged tried to burn down one the Crusader siege tower; the wind pushed the fire back against their own walls, causing a large section to collapse.

Raymond du Puy, the Grand Master of the Hospitallers, along with the Patriarch and the rest of the clergy, however, convinced the king that they were on the verge of victory.

After bitter fighting the city fell to the crusaders on 19 August, and the fortress was formally surrendered to them three days later on the 22nd, after the population was given time to leave.

[31] The increasing power of Jerusalem over the emirate of Damascus led Mujir ad-Din to start paying an annual tribute to the Crusader kingdom, though this was unpopular with his people.

[43] According to historian Malcolm Barber, had Amalric succeeded, a conquest of Egypt could have prevented the possibility of the Muslim encirclement of the Crusader kingdom that Saladin achieved in 1187.