The Siege of Jerusalem took place from June 7 to July 15, 1099 during the First Crusade. The climax of the First Crusade, the successful siege saw the Crusaders seize the city from the Fatimid Caliphate and laid the foundations for the Kingdom of Jerusalem.
Iftikhar ad-Daula, the Fatimid governor of Jerusalem, had expelled all of Jerusalem’s Christian inhabitants, so the Crusaders marched to Jerusalem.
On 7 June, the crusaders reached Jerusalem, which had been recaptured from the Seljuqs by the Fatimids only the year before. Many Crusaders wept upon seeing the city they had journeyed so long to reach. The crusaders put the city to a siege, in which the crusaders themselves probably suffered more than the citizens of the city, due to the lack of food and water around Jerusalem.
The city was well-prepared for the siege. Godfrey, Robert of Flanders, and Robert of Normandy (who had now also left Raymond to join Godfrey) besieged the north walls as far south as the Tower of David, while Raymond set up his camp on the western side, from the Tower of David to Mount Zion.
A direct assault on the walls on June 13 was a failure. Without water or food, both men and animals were quickly dying of thirst and starvation and the crusaders knew time was not on their side. Coincidentally, soon after the first assault, two Genoese galleys sailed into the port at Jaffa, and the crusaders were able to re-supply themselves for a short time. The crusaders also began to gather wood from Samaria in order to build siege engines. They were still short on food and water, and by the end of June there was news that a Fatimid army was marching north from Egypt.
The prime need of the crusaders was for ladders and siege towers to scale the walls of Jerusalem. The Egyptian Fatimid garrison had cleared the surrounding area of trees. The crusaders sent foraging parties into Samaria to obtain wood and other materials. They found 400 pieces of prepared timber, enough to build two 50 foot siege towers, a battering-ram and several catapults. A fleet of Genoese ships commanded by Guglielmo Embriaco, had arrived at Jaffa in support of the land-based crusaders. These vessels were dismantled by the Genoese, providing wood and ropes suitable for siege equipment, notably additional siege towers.
On the night of July 14, the crusaders launched a two-pronged assault on the walls. One tower was to the south, the other to the northwest. The Muslims knew that if one siege tower breached the walls, Jerusalem would fall. The Muslims pelted the first siege tower with flaming arrows and pots of oil until it went up in flames.
Now, only one siege tower was left, to the northwest under the command of the revered Duke Godfrey. Godfrey’s tower took two hours to reach the weak spot of the walls near the northeast corner gate. According to the Gesta two Flemish knights from Tournai named Lethalde and Engelbert were the first to cross into the city, followed by Godfrey, his brother Eustace, Tancred, and their men. Raymond’s tower was at first stopped by a ditch, but as the other crusaders had already entered, the Muslim guarding the gate retreated.