ed, for a considerable
breadth, with impervious thickets of _chapparal_. These thorny groves
are to be found in all sections of the south, varying in size from a few
yards to a mile in thickness, so closely interlaced and matted with
briers and bushes as to prevent the passage of animals larger than a
hare. They are the sorest annoyances of travellers in Mexico, and often
force the wayfarer to make a long circuit to pass their limits, though
they reward him for his trouble by supplying an abundance of the
_tuna_--a luscious fruit of the prickly pear,--which grows luxuriantly
on these natural and impenetrable walls.

Such, with the barrier of the stream, was the fortification nature had
interposed for the safe guard of Mexico at the Arroyo Colorado. But the
inert natives seemed indisposed to take advantage of those rare
defences, though not without some hostile demonstration which the
resolute conduct of Taylor soon overcame.

When our advanced corps encamped near the banks of the stream on the
19th, an armed _reconnoisance_ was sent forward to examine the country.
On reaching the river, our scouts discovered that the opposite side was
lined with a body of _ranchero_ cavalry, from whom they learned,
although no opposition was made to our examination of the ford, that we
should be treated as enemies if we attempted to pass it. Impossible as
it was to ascertain accurately the amount of the opposing force, our men
were prepared for the worst, and, at an early hour of the 20th, the
cavalry and first brigade of infantry were thrown in position, at the
ford, while the batteries of field artillery were formed so as to sweep
the opposite bank. All was now anxiety and eagerness among our gallant
men. Far along the borders of the river, above and below, the bugles of
the enemy were heard ringing out in the clear morning air. But the hope
of frightening our men by overwhelming numbers was of no avail. Our
pioneers worked steadily on the road they were cutting to the brink of
the river; and, when all was ready for the passage, the adjutant general
of the Mexican forces appeared on the ground for a final effort of
intimidation. With Spanish courtesy, he informed our general that
positive orders were given to his men to fire upon our forces if they
attempted to cross, and that our passage of the river would be
considered a declaration of war. At the same time he placed in Taylor's
hands a warlike proclamation issued by Mejia at Matam