In January, the First Crusade under Raymond IV of Toulouse, Robert of Normandy, Godfrey of Bouillon, Robert of Flanders and Tancred of Taranto began the long march south from the rolling point of Antioch. By June, the Christian Army of 12,000 knights and 11,000 foot soldiers reached Jerusalem. The city was held by a Moslem garrison under the caliph Al-Mustali of Cairo since the displacement of the Seljuk Turks the year before.

The city was well defended behind strong walls so the Crusades began constructing three giant siege towers while at night filling in the ditch at the base of the walls despite arrows and hurled stones. When this work was done they moved the towers to three different points; Raymonds in the south, Godfreys in the north and Tancreds in the northwest. Raymond's assault force at the south wall met with strong opposition and was checked. However at the north wall, Godfrey's men fought their way across the flying bridge and got inside the walls, opening the gate of Saint Stephen. The Crusaders poured into the city, launching a wholesale massacre of the Moslems and Jews. One account reports the death of as many as 71,000 by nightfall.

The objective of the First Crusade had been achieved. Jerusalem and all its holy places were in Christian hands, but the fighting was far from over.