The Mexican-American War happened from April 25, 1846, to February 2, 1848, and was about a disagreement between Mexico and the United States over land, especially Texas. Mexico believed the border between them was at the Nueces River, while the U.S. thought it should be at the Rio Grande after Texas joined the Union in 1845. Things got heated when Mexican troops fired on American soldiers at the Rio Grande, leading to the start of the war. This conflict changed the borders of North America forever.
From the United States' point of view, the war was seen as part of a larger idea called Manifest Destiny. This idea meant that Americans believed they were meant to expand across the continent and spread their way of life. President James K. Polk stated, "Our manifest destiny is to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.” Polk claimed that Mexico's actions were putting the U.S. at risk, and therefore, they had no choice but to defend themselves. Many Americans thought that gaining new land was necessary for their growing population and economy, especially in places like California and New Mexico, which were seen as important for farming and trade.
However, Mexico viewed the war very differently. They saw it as an invasion by the United States that violated their rights as a country. Mexican leaders argued that the annexation of Texas was illegal because it went against a treaty that recognized Mexico’s control over that land. As Mexican General Antonio López de Santa Anna remarked, “The American army is unjustly invading our territory, and the only thing we are doing is defending our homes and our dignity.” For Mexico, this war was about protecting their country’s honor and stopping the U.S. from taking more of their land. They felt that without a declaration of war, they were just trying to defend themselves from American aggression.
To decide whether the Mexican-American War was justified, we need to think about both sides. From the U.S. perspective, the war made sense as a way to expand and provide for a growing nation. But this way of thinking often ignores Mexico's rights and sovereignty. As historian Charles G. Sellers noted, "The war represented the triumph of expansionism over the principle of self-determination." On the other hand, Mexico's fight against U.S. expansion was about protecting their territory and dignity, making the war feel unfair to them. So, while the U.S. had reasons for going to war, it doesn't completely justify their actions because it overlooked the rights of another country.
In conclusion, the Mexican-American War shows us how complicated and messy expansion can be. While the U.S. justified their actions based on growth and opportunity, Mexico felt their nation was being attacked and disrespected. It’s clear that the war had serious consequences, and calling it justified is not easy. Understanding both perspectives helps us see that the motivations for war are often tangled and can lead to significant changes in history.