But all his precautions had not availed to shroud his designs from the vigilant foe, whose eye was on all his movements; who seemed even to divine his thoughts and to be prepared to thwart their execution. He had advanced but a few leagues, when he was met by a considerable body of Mexicans, drawn up to dispute his progress. A sharp skirmish took place, in which the enemy were driven from the ground, and the way was left open to the Christians. They held a circuitous route to the north, and their first point of attack was the insular town of Xaltocan, situated on the northern extremity of the lake of that name, now called San Christóbal. The town was entirely surrounded by water, and communicated with the main land by means of causeways, in the same manner as the Mexican capital. Cortés, riding at the head of his cavalry, advanced along the dike till he was brought to a stand by finding a wide opening in it, through which the waters poured, so as to be altogether impracticable, not only for horse, but for infantry. The lake was covered with canoes filled with Aztec warriors, who, anticipating the movement of the Spaniards, had come to the aid of the city. They now began a furious discharge of stones and arrows on the assailants, while they were themselves tolerably well protected from the musketry of their enemy by the light bulwarks with which, for that purpose, they had fortified their canoes. The severe volleys of the Mexicans did some injury to the Spaniards and their allies, and began to throw them into disorder, crowded as they were on the narrow causeway, without the means of advancing, when Cortés ordered a retreat. This was followed by renewed tempests of missiles, accompanied by taunts and fierce yells of defiance. The battle-cry of the Aztec, like the war-whoop of the North American Indian, was an appalling note, according to the Conqueror’s own acknowledgment, in the ears of the Spaniards.[343] At this juncture, the general fortunately obtained information from a deserter, one of the Mexican allies, of a ford, by which the army might traverse the shallow lake and penetrate into the place. He instantly despatched the greater part of the infantry on the service, posting himself with the remainder and with the horse at the entrance of the passage, to cover the attack and prevent any interruption in the rear.