By its natural position the city was exceedingly difficult to take by assault, for it stood upon a rocky plateau, guarded by the two steep valleys of Kedron and Hinnon.
It was, moreover, defended by about forty thousand picked Saracen warriors—a band equal in number to that of the besiegers, but possessing far greater advantages as to position and supplies.
With the utmost confidence, however, the Crusaders took up their posts. Robert of Normandy being stationed on the north, Godfrey of Bouillon and Tancred on the west, while Count Raymond advanced to Mount Sion on the south.
It was clear from the first assault that they had undertaken no light task, and meantime the usual horrors of famine and thirst made their appearance in the camp. There was little shade in that region; the groves around had been cut down to provide wood for the "machines of war," and the chief water supply—a spring which bubbled up every other day—was soon choked by the corpses of men and beasts who had trodden one another down in the wild attempt to obtain drink.
The springs further off had all been poisoned by the Saracens, and when the supplies of fruit began to fail, it seemed as though the army would never possess the strength to attack the city again.
A still worse calamity was the quarrelling which now broke out again among the leaders. Tancred was bitterly censured for having set up his banner over the Church of the Nativity at Bethlehem, Raymond for having taken to himself the post of honour on the sacred Mount of Sion. The rank and file, following the example of their chiefs, gave themselves over to laxity, disobedience, and personal feuds.
Once again it was necessary to invigorate the faith of the Crusaders, and accordingly Peter the Hermit declared that the dead Adhemar had appeared to him with words of severe rebuke for the sins of the camp, and the promise that the city should fall if the army would march barefoot round it for the space of nine days. A council was summoned, at which the noble Tancred was the first to make up a long-standing quarrel with Count Raymond; a feeling of good-will and reconciliation was spread abroad; and it was determined to make a fresh attempt in a spirit of more fervid religious zeal.
On the 12th of July 1099, while the Saracens were setting up crucifixes upon the ramparts, and insulting their Christian foes by spitting and throwing mud upon them, a solemn procession, fully armed, singing psalms and litanies, made its way around the walls; and a sermon preached from the Mount of Olives by Arnulf, the future Bishop of Jerusalem, roused even the most despondent to do his best for the cause of God.
On the next two days, Wednesday and Thursday, assaults were made, but without much success. On the Friday the Crusaders, having been reminded that it was the day of the Lord's Passion and Death, came to the work with new vigour, "even the women and the children," writes the historian, "were eager to do their part on that field."
But when Count Raymond fought on the south of the city it seemed as though success was hopeless. His wooden tower, which protected the archers, was burnt by the throwing of flaming oil from the walls, and his men were driven into utter confusion. Suddenly, when retreat seemed inevitable, a marvellous portent was seen. On the Mount of Olives, on the further side of the city, appeared a knight in glittering armour, waving a flaming sword over Jerusalem. The rumour quickly spread that it was St George come to the aid of the Crusaders. "Deus vult! Deus vult!" they shouted, and in the vigour of their assault the outer wall was won.