The little force was drawn in skillfully, and the horsemen on either flank began to retire from Agua Neva. The Mexicans, urged by Minon, Torrejon, Ampudia, and Santa Anna himself, pushed hard against the retiring force, seeking either to capture or destroy it. More than once they threatened to enfold it with their long columns, but here the horsemen, spreading out, held them off, and the long range rifles of the Americans were weapons that the Mexicans dreaded. As on many another battlefield, the Westerners and Southerners, trained from their boyhood to marksmanship, fired with terrible accuracy. The moonlight, now that their eyes had grown used to it, was enough for them. Their firing, as the slow retreat northward toward the Pass of Angostura went on, never ceased, and their path was marked by a long trail of their fallen foes. Santa Anna and his generals sought in vain to flank them, but the darkness was against the greater force. It was not easy to combine and make use of numbers when only moonlight served. Regiments were likely to fire into one another, but the small compact body of the Americans kept easily in touch, and they retreated practically in one great hollow square blazing with fire on every side. "Hold on as long as you can," Taylor had said to Marshall, but Marshall, in the face of twenty to one, held on longer than any one had dreamed. Santa Anna had expected to get his great cavalry force in the rear of Taylor at Agua Neva, but at midnight, finding Taylor not there and only a small detachment left, he had hoped to capture or destroy that in a few minutes. Instead, half his army was fighting a most desperate rear guard action with a few hundred men, and every second Marshall saved was precious to the commander back there at the Pass of Angostura. Phil was grazed by another bullet, and his horse was stung once. Arenberg was slightly wounded, but Breakstone was untouched, and the three still kept close together. The boy could not take note of the passage of time. It seemed to him that they had been fighting for hours as they gave way slowly before the huge mass of the Mexican army. Great clouds of smoke from the firing had turned the moonlight to a darker quality. Now and then it drifted in such quantities that the moon was wholly obscured, and then it was to the advantage of the Americans, who could fire from their hollow square in every direction, and be sure that they hit no friend. They had now left the town far behind and were well on the way to the Pass. Phil noticed that the fire of the Mexicans was slackening. Evidently Santa Anna had begun to believe that it would not pay to follow up any longer a rear guard that stung so hard and so often. This certainly was the belief of Bill Breakstone. "The pursuit is dying," he said, "not because they don’t want us, but because our price is too high.