Imagine if the U.S. invaded a country, conquered it after a savage conflict and gained about half of that nation’s territory in the treaty that ended the fighting.
That would seem memorable, right? Something that would be featured prominently in schoolbooks? The subject of novels and movies, maybe? A chapter in our national narrative?
Well, that conflict actually happened. But if you aren’t familiar with it, don’t be too hard on yourself.
The Mexican American War was a transformational event in U.S. history, expanding the nation’s reach to the Pacific coast and leaving it with territory that would eventually form all or part of 10 states, including Nevada.
But it’s largely forgotten among Americans.
“It really is overlooked, even among people living in places that were not that long ago part of Mexico,” said Penn State history professor Amy Greenberg, whose studies of the war led to her 2012 book, “A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico.” “I’ve been thinking about this question of why nobody knows anything about this war for a really long time.”
In the 170th anniversary year of the Treaty of Guadalupe Hidalgo, which ended the war, the Sun reached out to Greenberg and historian David A. Clary, author of the 2009 book “Eagles and Empire: The United States, Mexico, and the Struggle for a Continent,” to help explain why the war mattered, why it continues to matter and why it’s been relegated to a historical footnote. Here are some of their insights.
The war in about 200 words
When James K. Polk was elected U.S. president in 1844, the U.S. and Mexico were locked in a disagreement over land claimed by both Mexico and the Republic of Texas, which had won its independence in the fighting that included the Battle of the Alamo. Mexico said its territory extended to the Rio Nueces, while Texas claimed the border was about 150 miles south along the Rio Grande.
Amid the tension, Polk sent U.S. troops to the disputed area in 1845. A skirmish occurred in April 1846, which Polk claimed was as an attack on U.S. soldiers on American soil, and Congress declared war.
Over the next 16 months, regular U.S. forces and volunteers from state regiments marched into Mexico and also took control of California, which then was a Mexican territory.
In September 1847, Mexico City fell to the Americans, leading to the February 1848 Treaty of Guadalupe Hidalgo. In the treaty, Mexico ceded roughly half of its territory — an area that now makes up the entire states of Nevada, California and Utah, and parts of seven others. The U.S. agreed to pay Mexico $15 million and assume some of its debts.
Why the war was forgotten
Even while it was being fought, the war was unpopular among Americans.
One reason was that Polk’s premise in starting it would be uncovered as a lie.
Clary said the supposed attack was actually a random encounter between troops from both sides that were on routine patrol. In addition, Clary said Polk’s claim that the clash happened on American soil was specious.
“In international law, this is disputed territory. Countries that had this problem had to figure out a way to resolve the dispute,” Clary said. “Instead, Polk ordered (Gen. Zachary) Taylor to invade it. So right there was a violation of international law, and not the last one that was going to happen.”
Historians say Polk’s real motivation was to expand U.S. boundaries and gain control of the West Coast. To do so, he provoked Mexico into the war.
“He was an amoral man,” Clary said. “How he accomplished his goals wasn’t as important as just getting them accomplished.”
Greenberg said that unlike its two previous wars — the Revolutionary War and the War of 1812 — the U.S. wasn’t acting on noble principles in entering the Mexican American War. Not only was the U.S. fighting a smaller and less technologically advanced nation, but anti-Hispanic racial bias and anti-Catholic sentiment were factors in U.S. involvement. Another ugly motivation: Pro-slavery forces craved new territory where slavery could be expanded.
The war attracted a rush of volunteer forces, but the initial enthusiasm quickly fell off as fighting escalated.
Clary said both sides believed the other would be a pushover militarily, but that didn’t prove true. U.S. troops not only faced valiant Mexican soldiers but also were harassed by bandits who disrupted their supply lines and slowed their advance. Of the 79,000 Americans who took part, 17 percent died — one of the highest percentages of any war.
Meanwhile, troops concluded the territory wasn’t worth dying for, as much of it was arid and inhospitable.
As disillusionment set in and the advances slowed, another problem helped turn Americans against the war: atrocities committed by U.S. soldiers, mostly those from volunteer regiments.
Greenberg said discipline was lax among those troops, leading to rampant drunkenness and violent behavior.
“I was totally astounded by the number of killings of civilians — volunteers getting drunk, seeing an unarmed civilian and shooting them,” she said. “There were lots of fights and reports of going into Catholic churches and desecrating them. There were also reports of soldiers setting fire to entire villages and burning them down.”
Greenberg said rape of Mexican women and girls was so prevalent that Mexican officials believed it was a strategy “to terrorize the countryside.”
Notably to Nevadans, John C. Fremont, who is credited with being among the first whites to lay eyes on Nevada, was among the fighters associated with atrocities, in his case encouraging his soldiers to kill potential enemies as opposed to taking them prisoner.
Appalled by the war news and increasingly upset about the escalating cost of the conflict, Americans dialed up pressure on political leaders to end it. Although some hawks wanted to seize all of Mexico, and Polk wanted more territory than the U.S. would end up getting, the backlash helped push the U.S. into negotiations and end the occupation.
“It’s not a war that Americans are very proud of,” Greenberg said. “You know, it’s the only war that there’s not a monument to in Washington, D.C.”
From war with Mexico to war with each other
Another reason the war with Mexico sank into obscurity is that the Civil War simply muscled it out of U.S. history books.
Before and during the war, an uncomfortable question had simmered: Would slavery be extended to any new territory that would be gained from the fighting? After the treaty was signed, the simmering turned to a full boil.
“It turned slavery into an impossible problem — a problem with no solution,” Greenberg said. “With this incredible amount of territorial cessation, Southerners and Northerners were completely unable to compromise. Northerners are totally unwilling to see their territory, as they see it, with slaves in it. And Southerners believe it’s unconstitutional to not be able to bring their slaves into this territory. So not long after the war ends, Southerners start talking about secession.”
For that reason, historians see the Mexican American War as a major step toward the Civil War, which would break out just 13 years after the Treaty of Guadalupe Hidalgo.
The same holds true from a military standpoint, for which the war with Mexico was seen as a rehearsal for the Civil War. Many of the leading generals of the Civil War honed their tactics and strategy in the fighting against Mexico, including Ulysses S. Grant and William T. Sherman from the Union, and Robert E. Lee and Stonewall Jackson from the Confederacy.
Grant, in his memoirs, used the term that Greenberg borrowed for her book title — a wicked war — in describing the U.S.-Mexico conflict.
“For myself, I was bitterly opposed to the measure, and to this day regard the war which resulted as one of the most unjust ever waged by a stronger against a weaker nation,” Grant wrote. “It was an instance of a republic following the bad example of European monarchies, in not considering justice in their desire to acquire additional territory.”
Ramifications for Mexico
Mexico had been weakened during its war of independence decades earlier, and its defeat by the U.S. left it with a shattered military and a drastically reduced amount of territory. Deaths among combatants and civilians were estimated at 25,000.
Political dysfunction plagued the nation, as well. For example, Santa Anna served as Mexico’s leader seven different times between 1839 and 1855.
Amid the chaos, Mexico’s War of Reform broke out in 1857.
But on the other hand, Greenberg said, the war helped galvanize Mexico against a common enemy — the U.S. Before the war, she said, the nation had been deeply divided along economic and racial lines.
“So losing to these avaricious northern neighbors, it produces sort of a nationalism for the first time,” she said. “It makes people feel a kinship with each other that was absent before, so it’s really the beginning of the creation of the Mexican nation.”
Reverberations
In the same way that aftershocks of the Civil War can still be felt in the U.S. in such issues as the removal of Confederate statues and NFL sideline protests over racial inequality, Greenberg and Clary say the Mexican American War also continues to resonate through tensions over immigration and trade policies.
Unlike their neighbors to the north, the historians said, Mexicans grow up learning about the war, and the nation keeps the conflict’s memory alive through memorials and museums. Resentment toward the U.S. prying away Mexican territory still runs hot, Greenberg said.
“Every educated person in Mexico knows about and lives with the U.S.-Mexico war,” Greenberg said. “So every time they hear Donald Trump spouting anti-immigrant stuff, and they hear their president talking about how to react to the United States, this war is constantly in their mind. The animosity is still there. I think if people north of the border understood more about the war and why it happened and what the U.S. did when it took half of Mexico’s territory away from them, they might have a different perspective on the relationship we should have with Mexico.”
Clary agreed, saying the war continues to reverberate “everywhere south of the Rio Grande and in much of the Caribbean.”
“The United States, the colossus of the north, is not to be trusted,” Clary said.