To the disorganization of the Mexican state, rent by long
continued internal strife that rendered fairly impossible a real
unity of its people or any concert of action by its armed forces,
must be largely attributed the ease with which our little army
overcame all resistance. Yet these two campaigns, with the
very real difficulties that had to be surmounted in their prose-
cution, were excellent schools for the training of the officers
who, fifteen years later, bore the most conspicuous parts in
the bloody strife that was waged for four years between the
northern and the southern states. A roll of the most famous
and successful generals, both North and South, looks like a
promotion list of the younger officers of the war with Mexico.
After the close of this struggle the army returned to its
native soil and again scattered in small detachments, mainly
in the western country where, as settlement by the whites
proceeded with greater rapidity, it came to be more and more



112 HISTORY OF TWENTY-FIRST U. S. INFANTRY

in demand as a frontier police, doing its best to carry out the
mandates of the Government in Washington and to preserve,
as far as possible, a balance of peace between the Indian
tribes and the white settlers who pushed them from point to
point with careless aggressiveness.
Excepting the eight regiments of infantry raised for the
period of the Mexican War and disbanded in August, 1848, no
reduction or increase in the army took place until in 1855,
when the Ninth and Tenth Infantry, and the Fourth and Fifth
Cavalry were added under the provisions of the act of March
3rd of that year.
