As we began to experience that our daily advancing along the causeway each time cost us a loss of men, besides that we gained little advantage by it, for the Mexicans returned in the night, and again took possession of the points we had forced, we determined to alter our plan of operations, and took up a position on a more spacious part of the causeway, where several towers rose up together, and where we should be able to quarter ourselves for the night. Though we were miserably off here, and had nothing to protect us from the rain, nor to cover us from the piercing rays of the sun, we were not to be deterred from our purpose. The Indian females who baked our bread were obliged to remain behind in Tlacupa, protected by our cavalry, and the Tlascallans, who at the same time covered our rear, that the enemy might not fall upon us from the mainland. After these precautions had been adopted, we began to carry out our principal object, which was to make ourselves master of the houses in the suburbs, and of the intervening canals. These last were then immediately filled up, and the houses pulled down; for, as I have before mentioned, it was difficult to destroy them by fire, as they were detached, and stood in the water. It was from the tops of the houses that we received most injury from the enemy; so that, by destroying these, we gained a considerable advantage. Whenever we had taken one of the enemy's entrenchments, a bridge, or forced any other strong position, we were obliged to occupy the spot night and day with our troops, which we regulated in the following manner:--Each company watched by turns; the first from the evening time until midnight; the second from midnight until a couple of hours before daylight; and the third from that time till morning, when they were relieved by forty other men. The watch was each time relieved by a like number, though none of these watches left the spot; but when the following arrived, the former lay themselves on the bare ground, and took a little repose; so that when daylight came there were always one hundred and twenty men collected together ready for action. On other nights, when we expected some sudden attack, the whole of the men marched up at once, and remained under arms until the enemy approached. We had every reason to be upon our guard, for we learnt from several Mexican officers, whom we had taken prisoners in the different engagements, that Quauhtemoctzin and his generals had come to the determination of falling some day or night suddenly upon our encampment on the causeway; and concluded that, after they had destroyed us, they might easily make themselves masters of the two other causeways occupied by Sandoval and Cortes. To accomplish this finishing stroke, the nine towns lying in the lake, besides Tlacupa, Escapuzalco, and Tenayucan, were to cooperate with them. While we should thus be attacked on every side, they meant to