Question

What are 3 reasons why united states was not justified on going to war with mexico?

Answer 1

(1) Mexico started it, by attacking the army of General Zachary Taylor, who had been orderd to defend territory on the Rio Grande claimed by the United States as a consequence of the treaty between Texas and Mexico by which Texas first became independent.

(2) The US had tried to peaceably negotiate the disputed territory that had been part of Texas, by sending John Slidell to Mexico City, empowered to offer Mexico substantial amounts of money for the disputed territory.

(3) Even if the US had seriously provoked the war, and taken advantage of the fuzziness of the relevant treaties, the people in the relevant regions (Texas and Alta California) would be better off under American than Mexican rule, which was confused and corrupt at the time, with the Presidency rapidly changing hands and democratic traditions abandoned. In some cases, e.g. settlers who were originally American, those who lived in these regions actually had asked to be part of the United States. (Certainly this is true in the case of Texas.)

(4) The only basis by which Mexico could claim any superior right to rule these lands is that it had conquered them first. The Spanish aristocracy of Mexico had no "original settler" claim to these lands, since they had acquired them only by displacing and conquering the original Indian and Mesoamerican inhabitants. This is pretty thin stuff. If you want to say the United States was a thief to take California from Mexico, for example, the Mexicans only claim against that is that they stole it first, from the Indians. Not a very impressive moral claim.