During the first five or six days after their encampment the Spaniards experienced much annoyance from the enemy, who too late endeavored to prevent their taking up a position so near the capital, and which, had they known much of the science of war, they would have taken better care themselves to secure. Contrary to their usual practice, the Indians made their attacks by night as well as by day. The water swarmed with canoes, which hovered at a distance in terror of the brigantines, but still approached near enough, especially under cover of the darkness, to send showers of arrows into the Christian camp, that fell so thick as to hide the surface of the ground and impede the movements of the soldiers. Others ran along the western side of the causeway, unprotected as it was by the Spanish fleet, and plied their archery with such galling effect that the Spaniards were forced to make a temporary breach in the dike, wide enough to admit two of their own smaller vessels, which, passing through, soon obtained as entire command of the interior basin as they before had of the outer. Still, the bold barbarians, advancing along the causeway, marched up within bow-shot of the Christian ramparts, sending forth such yells and discordant battle-cries that it seemed, in the words of Cortés, “as if heaven and earth were coming together.” But they were severely punished for their temerity, as the batteries, which commanded the approaches to the camp, opened a desolating fire, that scattered the assailants and drove them back in confusion to their own quarters.[6] The two principal avenues to Mexico, those on the south and the west, were now occupied by the Christians. There still remained a third, the great dike of Tepejacac, on the north, which, indeed, taking up the principal street, that passed in a direct line through the heart of the city, might be regarded as a continuation of the dike of Iztapalapan. By this northern route a means of escape was still left open to the besieged, and they availed themselves of it, at present, to maintain their communications with the country and to supply themselves with provisions. Alvarado, who observed this from his station at Tacuba, advised his commander of it, and the latter instructed Sandoval to take up his position on the causeway. That officer, though suffering at the time from a severe wound received from a lance in one of the late skirmishes, hastened to obey, and thus, by shutting up its only communication with the surrounding country, completed the blockade of the capital.[7] But Cortés was not content to wait patiently the effects of a dilatory blockade, which might exhaust the patience of his allies and his own resources. He determined to support it by such active assaults on the city as should further distress the besieged and hasten the hour of surrender. For this purpose he ordered a simultaneous attack, by the two commanders at the other stations, on the quarters nearest their encampments.