The Spaniards waited until the foremost column had arrived within the best distance for giving effect to their fire, when a general discharge of artillery and arquebuses swept the ranks of the assailants and mowed them down by hundreds.[110] The Mexicans were familiar with the report of these formidable engines as they had been harmlessly discharged on some holiday festival; but never till now had they witnessed their murderous power. They stood aghast for a moment, as with bewildered looks they staggered under the fury of the fire;[111] but, soon rallying, the bold barbarians uttered a piercing cry, and rushed forward over the prostrate bodies of their comrades. A second and a third volley checked their career, and threw them into disorder, but still they pressed on, letting off clouds of arrows; while their comrades on the roofs of the houses took more deliberate aim at the combatants in the court-yard. The Mexicans were particularly expert in the use of the sling;[112] and the stones which they hurled from their elevated positions on the heads of their enemies did even greater execution than the arrows. They glanced, indeed, from the mail-covered bodies of the cavaliers, and from those who were sheltered under the cotton panoply, or _escaupil_. But some of the soldiers, especially the veterans of Cortés, and many of their Indian allies, had but slight defences, and suffered greatly under this stony tempest. The Aztecs, meanwhile, had advanced close under the walls of the intrenchment, their ranks broken and disordered and their limbs mangled by the unintermitting fire of the Christians. But they still pressed on, under the very muzzles of the guns. They endeavored to scale the parapet, which, from its moderate height, was in itself a work of no great difficulty. But the moment they showed their heads above the rampart they were shot down by the unerring marksmen within, or stretched on the ground by a blow of a Tlascalan _maquahuitl_. Nothing daunted, others soon appeared to take the place of the fallen, and strove by raising themselves on the writhing bodies of their dying comrades, or by fixing their spears in the crevices of the wall, to surmount the barrier. But the attempt proved equally vain.