There seemed to be something extraordinary happening amongst the Mexicans, to judge from the degree of confusion which suddenly showed itself in their ranks, and which, beginning with the cavalry and right flank of the infantry, soon became general throughout their whole force.  It was a sort of wavering and unsteadiness which, to us, was quite unaccountable, for Fanning and Wharton had not yet fired twenty shots, and, indeed, had only just come within range of the enemy.  Not knowing what it could portend, I called in my men, and stationed them round the gun, which I had double-shotted, and stood ready to fire.

The confusion in the Mexican ranks increased.  For about a minute they waved and reeled to and fro, as if uncertain which way to go; and, at last, the cavalry and right of the line fairly broke, and ran for it.  This example was followed by the centre, and presently the whole of the two battalions and three hundred cavalry were scattered over the prairie, in the wildest and most disorderly flight.  I gave them a parting salute from the eight-pounder, which would doubtless have accelerated their movements had it been possible to run faster than they were already doing.

We stood staring after the fugitives in perfect bewilderment, totally unable to explain their apparently causeless panic.  At last the report of several rifles from the island of trees gave us a clue to the mystery.

The infantry, whose left flank extended to the Salado, had pushed their right into the prairie as far as the island of muskeet trees, in order to connect their line with the dragoons, and then by making a general advance, to attack us on all sides at once, and get the full advantage of their superior numbers.  The plan was not a bad one.  Infantry and cavalry approached the island, quite unsuspicious of its being occupied.  The twelve riflemen whom we had stationed there remained perfectly quiet, concealed behind the trees; allowed squadrons and companies to come within twenty paces of them, and then opened their fire, first from their pistols, then from their rifles.

Some six and thirty shots, every one of which told, fired suddenly from a cover close to their rear, were enough to startle even the best troops, much more so our Mexican dons, who, already sufficiently inclined to a panic, now believed themselves fallen into an ambuscade, and surrounded on all sides by the incarnate diabolos, as they called us.  The cavalry, who had not yet recovered the thrashing we had given them, were ready enough for a run, and the infantry were not slow to follow them.

Our first impulse was naturally to pursue the flying enemy, but a discovery made by some of the men, induced us to abandon that idea.  They had opened the pouches of the dead Mexicans in order to supply themselves with ammunition, ours being nearly expended; but the powder of the cartridges turned out so bad as to be useless.  It was little better than coal dust, and would not carry a ball fifty paces to kill or wound.  This accounted for our apparent invulnerability to the fire of the Mexicans.  The muskets also were of a very inferior description.  Both they and the cartridges were of English make; the former being stamped Birmingham, and the latter having the name of an English powder manufactory, with the significant addition, “for exportation.”