But among the mass of information which the American General received at Puebla, his engineers learned that there was a pathway through this Pedregal whose route had been indicated by the spies with sufficient distinctness and certainty to justify a hope that he might be able to render it practicable for his whole army, and, thus, enable him to turn the right flank of the Mexicans' strongest positions. There is no doubt, as subsequent events demonstrated, that the ground in the neighborhood of Contreras, where the road descends from the mountains and barrancas towards San Angel was of great importance to the Mexicans in the defence of the various modes of access to the city, and it is unquestionable that a strong post should have been placed in that quarter to cripple the American advance. It is stated by Mexican writers, that General Mendoza, with two members of his topographical corps had reconnoitred this route and pass, and pronounced it "absolutely indefensible." It is probable, therefore, that no general action, involving the fortunes of a division, or of a large mass of the Mexican army, should have been risked among the ravines between the mountains and the Pedregal near Contreras; yet we do not believe that it should have been left by Santa Anna without a force capable of making a staunch resistance.
We are now acquainted with the ground, and with the positions of the two armies. Scott's plan was to force a passage by either or both of the two adits to the levels of the valley in front of the city, while Santa Anna's, according to his manifesto dated subsequently on the 23d of August, was to have made a concerted retrograde movement with his troops, and to have staked the fortunes of the capital on a great battle, in which all his fresh, enthusiastic, and unharmed troops would have been brought into a general action against the comparatively small American army, upon an open ground where he would have had full opportunity to use and manœuvre infantry, cavalry and artillery.
But this plan was disconcerted at first, and probably destroyed, both in its materiel and morale, by the gross disobedience of General Valencia, who forgot as a soldier, that there can never be two commanders in the field. Valencia, apparently resolving to seize the first opportunity to attack the Americans, in spite of the reported untenable character of the ground about Padierna or Contreras, left his quarters at Coyoacan and San Angel, and advanced, without consulting his commander, to Contreras, upon whose heights he threw up an entrenched camp! As soon as Santa Anna learned this fact, he ordered the vain and reckless officer to retire, but finding
