But they had scarcely begun their labors, when the hoarse echoes of conflict in the distance were succeeded by a hideous sound of mingled yells and war-whoops, that seemed to rend the very heavens. This was followed by a rushing noise, as of the tread of thronging multitudes, showing that the tide of battle was turned back from its former course, and was rolling on towards the spot where Cortés and his little band of cavaliers were planted. His conjecture proved too true. Alderete had followed the retreating Aztecs with an eagerness which increased with every step of his advance. He had carried the barricades which had defended the breach, without much difficulty, and, as he swept on, gave orders that the opening should be stopped. But the blood of the high-spirited cavaliers was warmed by the chase, and no one cared to be detained by the ignoble occupation of filling up the ditches, while he could gather laurels so easily in the fight; and they all pressed on, exhorting and cheering one another with the assurance of being the first to reach the square of Tlatelolco. In this way they suffered themselves to be decoyed into the heart of the city; when suddenly the horn of Guatemozin--the sacred symbol, heard only in seasons of extraordinary peril--sent forth a long and piercing note from the summit of a neighboring _teocalli_. In an instant, the flying Aztecs, as if maddened by the blast, wheeled about, and turned on their pursuers. At the same time, countless swarms of warriors from the adjoining streets and lanes poured in upon the flanks of the assailants, filling the air with the fierce, unearthly cries which had reached the ears of Cortés, and drowning, for a moment, the wild dissonance which reigned in the other quarters of the capital.[47]