The most likely reason for this part of American history being skipped is because the war does not project the image of how we want to be viewed as Americans. In a nutshell, American president James K. Polk wanted to expand the American territory to the Pacific Ocean. So he offered to buy the land which today makes up the states of California, Nevada, Utah, Arizona, New Mexico, and parts of Texas and Colorado. When the Mexican government refused to sell, America declared war and took the land.
At first, the public was in great favor of the war and many young men signed up to fight. In what is today Texas, the Mexican government identified the Nueces River as the boundary between the two countries. The Americans however, recognized the Rio Grande River as the boundary despite the fact that the majority of people living in the disputed land identified themselves as Mexicans. Around the time the Americans put in their offer to purchase the Northern half of Mexico, the Mexican Army killed a handful of American soldiers and captured about 50 more on land in the disputed territory. The incident was widely publicized and the government had public support.
For nearly two years, the countries fought battle after battle. As the war lingered on, public support dwindled. The people began to realize the initial reason for the declaration of war was in great part presented to appear as if the Americans were defending their liberties, when in fact, they were fighting to take land they desired which was not for sale.
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