The mexican-american war was from April 25, 1845, to February 2, 1848, not many people know about this war because the USA doesn't like to talk about it. This was a really tragic war for Mexico because they lost half their land which is now ours.
Before the mexican-american war, Mexico used to own texas the USA had brought 300 families to texas to harvest the land, Mexico later banned slavery which was a huge income for America and that meant that they couldn't have slaves in texas so they started to rebel, and later with the help of the USA as an independent country, but later joined the USA after many years of trails waiting to become a state of the united states of America.
After Texas left Mexico, America had a desire to expand from sea to sea, so America wanted to buy Mexican land for 30 million dollars but Mexico refused because they were not selling their land. And so America was going to get that land one way or another so they lined their troops along el Rio grande and Mexico still thought they owned that land, Mexico attacked first in desperation to protect their country.
Later into the war, Mexico was losing because the USA had tried new cannon technology by adding a cannon to a horse and that made them move faster, they could get cannon to areas faster than Mexico. Also, Mexico was going through a rebellion because they had no public education and the Mexican people thought that was important.
Mexico did end up losing the war and ended giving most of their land to the usa and america did end up giving 15 million of dollars to mexico, later the american people started moving west, which really helped the usa flourish and be one of the greatest nations.
After all this war president pope was not justified because he went to war because he felt like the west was meant for the people of the usa and we did flush but at what cost mexico suffering because of us.