[Restorer]

You can also make a good historical case that the Mexican and Spanish-American wars were unprovoked. Not to mention dozens of little interventions in Latin America and the Caribbean.

[Burkeman1]

That case can be made. But Mexico was a paper Empire. They had virtually no presence in the vast territories in Texas and the Southwest/California. They were a de facto fuedal society that was inudated with free western farmers and ranchers who were not about to put up with rule from Mexico city that was arbitrary, corrupt, and authoritarian.