After father Juan Diaz had said mass, we commended ourselves to the protection of the Almighty, and both divisions marched forward to cut off the aqueduct of Chapultepec, which lies about two miles from Tlacupa, and supplies Mexico with water. On our way thither, we fell in with several bodies of Mexicans, who had received intelligence that this was to be the commencement of our operations against Mexico. The enemy had in every way the advantage ground over us, and attacked us vigorously with lances, arrows, and stones, by which three of our men were wounded; but we soon put them to flight, and they were so closely pursued by the Tlascallans that they lost twenty killed, and seven or eight were taken prisoners. We were now able to destroy the aqueduct without any further opposition, and the city of Mexico was deprived of this source of obtaining water during the whole of the siege. As soon as we had destroyed this aqueduct, our officers determined to make an attempt upon one of the bridges on the causeway leading from Tlacupa. We had scarcely begun to move along the causeway when numbers of canoes, filled with troops, advanced swiftly from both sides, while other large bodies of the enemy came marching up the causeway against us, so that we were quite astounded at the very sight. In the first encounter thirty of our men were wounded and three killed. Notwithstanding all this, we fought our way up to the first bridge. According to what we afterwards heard, it was the wish of the Mexicans that we should pass over the bridge; for we had no sooner done so than we were assailed by such terrific crowds, as to be unable to move. What indeed could we do on a causeway which was no more than eight paces in breadth, where we were attacked on all sides at once? Our crossbow-men and musketeers certainly kept up a continued fire on the canoes, but the enemy received but a trifling loss this way, for they had raised boards alongside of their canoes, by which their troops were sheltered from our fire. Those of the enemy's troops which attacked us on the causeway itself we certainly drove back each time into the water, but fresh troops kept pouring in too fast for us to gain much advantage this way. Here our cavalry was of no manner of use to us, while the horses were greatly exposed to the attacks of the enemy on each side of the causeway, and many were consequently wounded. If our cavalry attempted to pursue the enemy into the water, the latter had provided against this by palisades, behind which they retired, and stretched out against them their long lances, to which they had fastened the swords we unfortunately lost on our retreat from Mexico.