So effectually were they kept in order, that the Mexicans confessed that it was a smaller evil to have the enemy's forces marching through the country, than their own army.
An elaborate account of the American invasion is given in Mayer's 'Mexico.' To those who do not care for details of military operations, there are still points of interest in the history.

That ten thousand Americans should have been able to get through the mountain-passes, and to reach the capital at all, is an astonishing thing; and after that, their successes in the valley of Mexico follow as a matter of course.
They could never have crossed the mountains but for a combination of circumstances.
The inhabitants generally displayed the most entire indifference; possibly preferring to sell their provisions to the Americans, instead of being robbed of them by their own countrymen.

Add to this, that the Mexican officers showed themselves grossly ignorant of the art of war; and that the soldiers, though they do not seem to have been deficient in courage, were badly drilled and insubordinate.

One would not have wondered at the army being in such a condition---in a country that had long been in a state of profound peace; but in Mexico a standing army had been maintained for years, at a great expense, and continual civil wars ought to have given people some ideas about soldiering.

We may judge, from the events of this war, that Mexico might be kept in good order by a small number of American troops.