Cortes Explains Why Spaniards Can't Stay in Tenochtitlan Overnight
From Cortés, Third Letter, 281–83
On the following day, at an early hour of the morning, after hearing mass, I returned to the city in the same order with my whole force, so that the enemy might not have time to open the breaches in the road, and throw up entrenchments; but although we were early on the ground, of the three water-streets that crossed the road leading from the camp to the large houses on the square, two were in the same condition as on the previous days, and extremely difficult to be taken; the combat lasted from eight o'clock till one in the afternoon, during which time all the arrows and balls carried by the archers and musketeers were exhausted. Your Majesty may well believe that the danger was very great to which we were exposed every time we gained these bridges, since in order to accomplish it the Spanish soldiers were obliged to throw themselves into the water and swim to the opposite side; this could not be done, nor attempted by all, as the enemy stood ready to oppose their landing by slashing them with knives or thrusting lances at them. But as they no longer had terraces from which to annoy us on the opposite quarter, and we kept up a shower of arrows from our side, the distance apart being but the cast of a horseshoe, the Spaniards early in the day took fresh courage, and determined to pass, especially when they saw that this was my determination likewise, and that, sink or swim, the thing must be effected. It will perhaps appear to your Majesty that as we encountered so much peril in gaining these bridges and entrenchments, we were guilty of neglect in not retaining them after we had once succeeded in taking them, and thus avoiding the daily return anew to so much danger and toil, which were unquestionably great, as they must appear to those not present. But your, Majesty should know that this was impossible, for in order to accomplish it two things were necessary--either that we should remove our camp to the great square containing the temples of the idols, or that our people should guard the bridges by night--both of which would be attended with great danger, and found to be impracticable. Should we encamp in the city, every night. and every hour the enemy would surprise us with sudden attacks, and being themselves numerous and we but few, the labor would be insupportable to resist them on all sides. Then as to guarding the bridges by night, the Spaniards are so fatigued by fighting through the day, that none, of them are fit to perform guard-duty, at night; we were therefore compelled to retake them everyday that we entered the city.
On this day, as there was much delay in gaining the bridges, and in returning to fill up the water, there was no opportunity to do more than to take two other bridges on the other principal street leading to the city of Tacuba, which we filled up, and afterwards burned many houses on that street. By this time it was evening, and the hour to return to camp, which was attended with little less danger than taking the bridges; for as soon as they saw us retire, the inhabitants recovered themselves to such a degree that it seemed as if they had been victorious, and that we were flying before them; it was likewise necessary for our safe return, that the space occupied by the bridges should be well filled up so as to be even with the street, that the cavalry might be able to move freely from one side to the other. Sometimes when thus returning to camp, and the enemy pursued us so ravenously, we would pretend to fly, and then turn about suddenly upon them, and take twelve or thirteen of the boldest of them prisoners. By these means, and the ambuscades we laid for them, into which they were constantly falling, they always suffered; and their conduct worthy of admiration, for however great the evils and losses to which they were exposed in harassing our march, they did not relax their pursuit till they saw us out of the city. Thus we returned to our camp, when the captains of the other posts informed me they had succeeded well the same day, and had destroyed many of the enemy by land and, water; ...