Research Feature: The Forgotten War

Gigi Marino
August 10, 2010
Historian Amy Greenberg behind desk
Amy Greenberg

Amy Greenberg

According to the book "Game Change," when political advisers sat down with Sarah Palin “to give her a potted history of foreign policy,” they began with the Spanish-American War, which, in fact, was not this country's first foreign war. The omission of the U.S-Mexican War from the list of U.S. engagements—in popular nonfiction, history books, or "Jeopardy!" questions—does not surprise historian Amy Greenberg, who seeks to bring this pivotal conflict into the frontal lobe of the American consciousness.

The U.S.-Mexican War of 1846 was a horrific, bloody, 16-month battle predicated on greed, expansion and imperialism, said Greenberg, Penn State professor of American history and women’s studies. “Though both its justification and consequences are dim to us now,” she said, “this, our first war for empire, decisively broke with our past, shaped our future, and, to this day, affects how we act in the world.”

In a book she is writing on the subject, with the support of a 2009 Guggenheim Fellowship, Greenberg points to four key players who initiated, mediated and ended the war. President James K. Polk rallied for war against Mexico, claiming that our southern neighbors had killed American soldiers on American land. Senator Henry Clay publicly denounced the war, sparking what Greenberg calls “America’s first national anti-war movement.” Illinois Representative Abraham Lincoln, who admired Clay and also opposed the war, learned invaluable lessons in power and morality. Nicholas Trist was a diplomat who disobeyed an executive order to leave Mexico and instead brokered the Treaty of Guadalupe Hidalgo, which, effectively, ended both the war and his diplomatic career.

A Manifest Reason for War

The U.S.–Mexican War began in the roiling wake of the Texas Revolution, which had led to the creation of the Republic of Texas in 1836. The Mexican army had been ruthless, creating a decade of hostility leading up to the U.S.–Mexican War. The rage of anti-Mexico sentiments, coupled with the popular belief in Manifest Destiny and the pro-slavery states’ desire to expand slave-owning territories, produced an incendiary political climate. And James Polk, with a claim of Mexican aggression, provided the flashpoint.

painting of an angel above a war scene

“Spirit of the Frontier,”by John Gast (1872), was a popular allegory of Manifest Destiny. This painting and the painting in the lead image,"The Battle of Veracruz,"by Carl Nebel (1851), via Wikipedia.

“When President Polk called for volunteers to fight a war against Mexico, even if most Americans didn’t fully believe his claim that Mexicans had ‘shed American blood on American soil,’ they believed that it was our Manifest Destiny to expand across the continent,” said Greenberg. “Powerful business interests in the Northeast were interested in acquiring the ports of California. Pro-slavery voters were looking to expand their territory, but some of the most enthusiastic volunteers had no investment in slavery. Young American men in Midwestern states like Illinois turned out in great numbers. They had been raised on tales of Mexican atrocities at the Alamo and Goliad and looked forward to the opportunity to avenge those wrongs by killing some Mexicans.”

Greenberg said that when the call for volunteers first went out, the U.S. Army was forced to turn away hopeful recruits. “People thought the war would last for three months. The war wasn’t close to being over after the first year. And those who eagerly signed up in 1846 did not want to go back.” No one imagined that the Mexican soldiers, thought by Americans to be feeble and inferior, would be as tenacious as they were.

Recovering a History That Was Never Lost

Greenberg, a scholar of pre-Civil War America, first became interested in writing about the U.S.-Mexican War when she was working on a book on Manifest Destiny. She said she couldn’t find an authoritative text on the subject, despite numerous collections of primary resources, and decided to write one herself.

“In our own library, there are 50 separate volumes of primary sources, letters or diaries of soldiers from the U.S.-Mexican War,” she said, “and yet we know nothing about these experiences.”

Actually, many of those 50 volumes temporarily reside in Greenberg’s office on the third floor of Weaver Building, where she re-tells these narratives with the enthusiasm of a war correspondent. “Look at this,” she said. “Here’s the story of an embedded journalist who called himself ‘John of York’ writing for the Philadelphia North American, who started off as a foot soldier, then became an officer. The embedded journalists’ reports are awesome. They talk openly about atrocities committed by U.S. troops on Mexican civilians, about disease killing the soldiers themselves. They report actual accounts of these bloody battles that witnessed a large loss of life, with people on both sides dying.”

soldier being pulled off of downed horse at war
Painted by Chappel. Engraved by Phillibrown. 1858.

"The Death of Major Ringgold at the Battle of Palo Alto"

The stories told by the world’s first embedded correspondents are just one of the many firsts Greenberg attributes to the U.S.-Mexican War. Others include: the first war started with a presidential lie; America’s first foreign conflict; the first war for land, not principle; the highest casualty rate of any American conflict before or since; our first military occupation of a racially and linguistically foreign populace; the first time the reputation of American troops was damaged; and the first time war was turned into entertainment through the publication of thrilling daily narratives starring a cast of heroes.

“You have to remember,” she said, “that newspapers then were like the CNN of today.” Americans of the time were left with brutal images.

Amnesia and More

Why do we forget this important chapter of America’s past?

Simply, said Greenberg, such a war for empire does not fit into the American narrative. “It was a land grab. There was no principle at stake,” she said. “The United States does not see itself as a country that goes to war and takes from other nations, particularly not from neighboring republics.”

Yet, what this war birthed was a powerful anti-war movement and a future president who found the wisdom, in the shadow of imperialism, to hold a sovereign nation together on principle, rather than power. “Our unjust war of imperial desire shoved us into the most horrible of national fractures,” said Greenberg, “yet, at the same time, shaped the man who was able to save us.”

At the bitter end of the war, the commander in charge, General Winfield Scott, captured Mexico City and immediately realized that this capture was folly. Mexican snipers picked off his cavalrymen as they attempted to carry the reports of embedded journalists in their saddlebags to the port of Vera Cruz. The land grab worked best in isolated areas; Scott and diplomat Trist knew this well. Both believed that prolonging the war would only escalate guerilla fighting. Trist followed his moral compass, and when Polk ordered his return to Washington, he gambled everything to stay and continue negotiating.

“Trist returned from Mexico to face the enduring contempt of Polk,” says Greenberg. “The president might sign his treaty but he would give him no credit for it. He fired the ‘impudent and unqualified scoundrel’ and withheld his pay.” Yet, Trist, unwittingly or not, conserved the sanctity of this nation, and unwittingly or not, set into play a foreign policy that remains with us today, said Greenberg.

“Mexico lost half its territory—about 500,000 square miles. Gone were the provinces of Alta California, Nuevo Mexico, and parts of Tamaulipas, Coahuila, and Sonora. That land became California, Nevada, and Utah, and parts of Texas, Arizona, New Mexico, and Colorado,” she said. “It was the crowning moment for Manifest Destiny, and fed the dreams of those Americans who believed we should take even more territory from neighboring countries by force—dreams that had their realization in the Spanish-American War.”

Amy Greenberg, Ph.D., is professor of American History and Womenís Studies in the College of the Liberal Arts. She can be reached at Her research is supported by the John Simon Guggenheim Memorial Foundation and the American Philosophical Society and her book on the U.S.-Mexican War is due out in 2012 from Knopf. Greenbergís book, Manifest Manhood and the Antebellum American Empire, was published by Cambridge University Press in 2005.

Last Updated August 10, 2010