The Crusaders besieged Jerusalem on June 7, 1099, exactly a year after their siege of Antioch. Between Antioch and Jerusalem, they had passed by Fatimid-ruled cities but these governors had permitted them to go without opposition. The Fatimids abandoned Jaffa on the coast and concentrated all defenses inside Jerusalem.
Jerusalem is situated on a hilly plateau on the eastern edge of the Great Rift Valley’s last rift. King David had captured it because of its location; it was a natural stronghold, unlike coastal Jaffa. Attackers always wanted to find some point looking down on the city, and it was difficult with Jerusalem. The Mount of Olives and Mount Zion were both just outside the city walls, but some other approaches to the city were impassible. The princes grouped in roughly three forces under Raymond, Godfrey, and Tancred the nephew of Bohemond, who had risen in status during the Crusade. Tancred was intent on becoming a prince in the Holy Land; he wanted to do what Bohemond had done in Antioch, becoming the personal conqueror and subsequent ruler. The Duke of Normandy and Count of Flanders were content to be part of Tancred’s forces, although they may not have viewed it quite like that.
The army needed siege engines, but they were in a land without good timber. They solved the problem by purchasing some Genoese ships docked at Jaffa. The ships, dismantled, provided them enough timber to make three wheeled siege engines, ladders and some catapults. The siege engines were built on the plain and then reassembled on the hilltops near city walls.
As they prepared and planned for the big assault, a priest had a vision from Adhemar Le Puy, the Papal Legate who died of typhus a few months earlier at Antioch. He suggested that the Crusaders should imitate Joshua by marching around Jerusalem. The men fasted for three days and then walked barefoot around the city. At nightfall on July 13, 1099, they began the attack.
While catapults hurled missiles from both sides of the city walls, the Crusaders filled in defensive ditches meant to keep out wheeled siege engines. The first siege tower went up against the wall on Mount Zion, but the Egyptian forces defended the wall fiercely. Godfrey of Bouillon suddenly noticed in the pre-dawn light that the north-eastern gate was not well defended. While Raymond’s men kept up the attack on Mount Zion, other forces rushed siege engines to this new point. At dawn, both attacks were pressed simultaneously. The Fatimid forces were not able to keep up both defenses, and by mid-day, Godfrey crossed from his siege engine to the top of the wall. The first men into the city flung open the gate that’s now where the Damascus Gate is located. (The city walls from 1099 were destroyed completely in 1244, and later rebuilt in 1538, so old as the current gates are, they are not the same ones that Godfrey flung open.)
Tancred’s men rushed in, cheering. On Mount Zion, the men of Provence heard the cheering and raced to enter the city lest the Normans get all the spoils. Within a few days, all of the city’s residents and defenders were dead. This may not be truly accurate; chroniclers of the conquest of Jerusalem were eager to magnify the slaughter, writing like fans of a winning Superbowl team. But from what historians can tell, it was probably true enough.
Tancred aspired to rule Jerusalem. He wanted to be in control of the city’s sacking; as part of this, he wanted to spare a small group of Fatimid defenders. When he discovered about 300 men (many North Africans) crowding onto the roof of Al-Aqsa Mosque, he posted his banner there, placing them under his protection. They remained there overnight, as massive slaughter went on all around them. Thousands of Muslim clerics, families with small children, and groups of Jews were killed. Some Jews hid in a synagogue, which the Crusaders burned down. But in the morning, men under Raymond of Toulouse climbed onto Al-Aqsa, took down Tancred’s banner, and slew the men there. Raymond was not going to allow Tancred that sort of sovereignty.
In a last sweep of the city, knights killed the inhabitants of houses they liked and marked the houses with their arms. There were some survivors who got ransomed by the Fatimids, and some survivors who were forced to clean up and bury the dead. But to a great extent, the city was left deserted. Simon Sebag Montefiore, in his book about Jerusalem, says that the Crusaders had to go outside the city into the eastern countryside and find local Christian peasants to move in. These, he said, became the medieval Arab population. Jews did not come back into the city until Saladin retook it in 1187.
Jerusalem had not been conquered in such a devastating way since 70 AD. When the original Muslim conquest took place, its leaders were interested in mostly leaving city economies intact so that they could tax them. The Crusaders’ victory was ideological. Their vision of Jerusalem did not include Muslims or Jews; their idea of diversity meant Armenian Christians, Latin Christians, and Greek Christians. It was part of the hardening of ideology in this period; it set a bloody precedent.