Excerpts from Books and Wikipedia
"It was more than two years since the army--mostly made up of French knights and nobles, with a contingent of Normans from south Italy--had left Constantinople to begin the long march to Jerusalem. . . . All this time the crusaders had been fighting the Seljuk Turks, but now they were making their way into the territory of the Fatimid caliphs of Cairo, who had retaken Jerusalem from the Seljuks in August 1098. By the time the weary crusaders encamped in front of Jerusalem on June 7, 1099, only 1,200 knights remained of the 7,000-strong army that had initially set out. . . . Over the course of the next two days, the crusaders indiscriminately murdered almost every inhabitant, be they Muslim or Jew, and even some Eastern Christians. Even those who had taken shelter in the Al Aqsa Mosque were ruthlessly slaughtered. Geoffrey of Bouillon became the new Christian governor of the city." [1001 Days]