Taking a southerly direction, the troops, after leaving Chalco, struck into the recesses of the wild sierra, which, with its bristling peaks, serves as a formidable palisade to fence round the beautiful Valley; while within its rugged arms it shuts up many a green and fruitful pasture of its own. As the Spaniards passed through its deep gorges, they occasionally wound round the base of some huge cliff or rocky eminence, on which the inhabitants had built their towns, in the same manner as was done by the people of Europe in the feudal ages; a position which, however favorable to the picturesque, intimates a sense of insecurity as the cause of it, which may reconcile us to the absence of this striking appendage of the landscape in our own more fortunate country. The occupants of these airy pinnacles took advantage of their situation to shower down stones and arrows on the troops as they defiled through the narrow passes of the sierra. Though greatly annoyed by their incessant hostilities, Cortés held on his way, till, winding round the base of a castellated cliff occupied by a strong garrison of Indians, he was so severely pressed that he felt to pass on without chastising the aggressors would imply a want of strength which must disparage him in the eyes of his allies. Halting in the Valley, therefore, he detached a small body of light troops to scale the heights, while he remained with the main body of the army below, to guard against surprise from the enemy. The lower region of the rocky eminence was so steep that the soldiers found it no easy matter to ascend, scrambling, as well as they could, with hand and knee. But, as they came into the more exposed view of the garrison, the latter rolled down huge masses of rock, which, bounding along the declivity and breaking into fragments, crushed the foremost assailants and mangled their limbs in a frightful manner. Still they strove to work their way upward, now taking advantage of some gully worn by the winter torrent, now sheltering themselves behind a projecting cliff, or some straggling tree anchored among the crevices of the mountain. It was all in vain. For no sooner did they emerge again into open view than the rocky avalanche thundered on their heads with a fury against which steel helm and cuirass were as little defence as gossamer. All the party were more or less wounded. Eight of the number were killed on the spot,--a loss the little band could ill afford,--and the gallant ensign, Corral, who led the advance, saw the banner in his hand torn into shreds.[366] Cortés, at length, convinced of the impracticability of the attempt, at least without a more severe loss than he was disposed to incur, commanded a retreat. It was high time; for a large body of the enemy were on full march across the Valley to attack him.