On the 15th of the month, the army neared Las Vegas; when two spies who had been sent on in advance to see how matters stood returned and reported that two thousand Mexicans were camped at the pass a few miles beyond the village, where they intended to offer battle. Upon receipt of this news, the general immediately formed a line of battle. The United States dragoons with the St. Louis mounted volunteers were stationed in front, Major Clark with the battalion of volunteer light artillery in the centre, and Colonel Doniphan's regiment in the rear. The companies of volunteer infantry were deployed on each side of the line of march as flankers. The supply trains were next in order, with Captain Walton's mounted company as rear guard. There was also a strong advance guard. The cartridges were hastily distributed; the cannon swabbed and rigged; the port-fires burning, and every rifle loaded. In passing through the streets of the curious-looking village of Las Vegas, the army was halted, and from the roof of a large house General Kearney administered to the chief officers of the place the oath of allegiance to the United States, using the sacred cross instead of the Bible. This act completed, on marched the exultant troops toward the canyon where it had been promised them that they should meet the enemy. On the night of the 16th, while encamped on the Pecos River, near the village of San Jose, the pickets captured a son of the Mexican General Salezar, who was acting the role of a spy, and two other soldiers of the Mexican army. Salezar was kept a close prisoner; but the two privates were by order of General Kearney escorted through the camp and shown the cannon, after which they were allowed to depart, so that they might tell what they had seen. It was learned afterward that they represented the American army as composed of five thousand troops, and possessing so many cannons that they were not able to count them. When Armijo was certain that the Army of the West was really approaching Santa Fe, he assembled seven thousand troops, part of them well armed, and the remainder indifferently so. The Mexican general had written a note to General Kearney the day before the capture of the spies, saying that he would meet him on the following day. General Kearney, at this, hastened on, arriving at the mouth of the Apache canyon at noon, with his whole force ready and anxious to try the mettle of the Mexicans in battle. Emory in his _Reconnoissance_ says: