Sandoval, on receiving this information, concluded that there was no time to be lost, and immediately marched towards Chimalhuacan, which was subject to Chalco, where he quartered his troops for the night. The inhabitants of Chalco had sent out spies in every direction, and learnt that the enemy was not far off, but lay in wait for the Spaniards in the thickets and hollows of the mountains. Sandoval, who was an officer of great determination and foresight, ordered his march as follows: the musketeers and crossbow-men went in advance, the cavalry were to follow three and three together, and when the former had discharged their pieces, the horse were to charge the enemy's line at full gallop, and to direct the point of their lances at the face, and continue the attack until the enemy was put to flight. The infantry were to keep their ranks firmly closed, and not to rush in upon the enemy until a signal for that purpose was given. This order of attack Sandoval deemed necessary, as the enemy's numbers were very great, and the nature of the ground unfavorable for his manoeuvres; besides that, it was impossible to discover whether the Mexicans had not dug pits or laid other snares to entrap the Spaniards; so that it was quite necessary his small army should keep close together in a body. After Sandoval had marched a little further on he came up with the Mexicans, who were advancing towards him in three distinct bodies, with fearful yells and the horrible din of drums and shell trumpets, and instantly fell upon our troops like so many furious lions. As soon as Sandoval observed that the enemy intended to fall upon him in three distinct bodies, he likewise changed his order of attack, and commanded the cavalry to charge the foe without delay, and not wait for the rest of the troops. He then placed himself at their head, encouraged his men and rushed forward to the attack, under the cry of--"Santiago!" The powerful shock which the enemy thus sustained certainly caused some of them to recoil, but they immediately closed again and boldly advanced against our horse, being greatly assisted by the unevenness of the ground and a deep break, where it was difficult for our horse to manoeuvre. Sandoval, perceiving the enemy's advantage, ordered his foot to close their ranks again, placed the crossbow-men and musketeers in front, and those who were armed with swords and shields on the flanks. In this order they were again to advance to the attack as soon as they heard a shot from the other side of the break, which would be a signal to them that the cavalry had charged and driven the foe back on to the level ground. Our allies were likewise ordered to follow the example of the Spanish foot; this was accordingly done and the object accomplished.