Long after we are dead," wrote the popular mid-19th-century novelist George Lippard, "History will tell the children of ages yet to come, how the hosts gathered for the Crusade, in the year 1846."
One hundred and fifty years ago, the United States took up arms against Mexico, engaging in a war fought wholly on foreign soil for the first time in its history. It was a conflict fraught with significance for both nations. Yet for all its importance (and despite Lippard's confident prediction), the war with Mexico has become America's forgotten war. Few today can recite its causes. Few Americans even recall the battlefield triumphs. If remembered at all, it is thought of, wrongly, as an unpopular war, in large part because certain luminaries of the day, including Ralph Waldo Emerson and Henry David Thoreau, inveighed so eloquently against it.
To be sure, wars often create more problems than they settle, and the Mexican War was no exception. A bitter and divisive sectional struggle over the issue of slavery's expansion into the territories gained from Mexico was an unintended consequence of the conflict. Many Americans were later convinced, as was Ulysses S. Grant (himself a participant in the war), that "the Southern rebellion was largely an outgrowth of the Mexican War." Writing 40 years after the fact, failing in health, the old general influenced much subsequent thinking about the war when he charged that it was "one of the most unjust ever waged by a stronger against a weaker nation." The Civil War, he declared, was "our punishment." The war with Mexico, when it was viewed at all, was considered within the context of the struggle over slavery and as a precursor to what Grant called "the most sanguinary and expensive war of modern times."
But the Mexican War had importance far beyond its contributions to the outbreak of the Civil War - and in its day was viewed far more favorably than subsequent opinion would have us think. The first major national crisis faced during a period of unprecedented economic and social change, it came at a crucial moment in the young life of the United States. Rapid commercial and industrial expansion, with new opportunities for material advancement, was changing people's lives. Social reformers, utopian visionaries, political theorists, and religious enthusiasts were offering a host of projects and schemes in their quest for individual improvement. Questions were being raised about the true nature and purpose of republican government, as older values of patriotism and civic virtue - the heart of classical republicanism - seemed to be giving way before the new "spirit of gain."
The United States at midcentury was a nation in search of itself, and the war with Mexico became an important step toward self-definition. For a time and for some people, the war offered reassurance, giving new meaning to patriotism, providing a new arena for heroism, and reinforcing popular convictions regarding the superiority of republican government. The war was seen as a test of democratic institutions, as legitimizing America's mission as the world's "model republic."
The outbreak of the Mexican War had a long and complex background in years of uneasy relations between the two countries. To many Americans, the frequency of revolutions in Mexico rendered that country's republican government more a sham than a reality. The United States had lodged claims against Mexico for losses incurred by American citizens during the revolutions, but even though the claims were arbitrated in 1842 at Mexico's request, they remained unpaid.
Yet for all the moments of irritation and tension, the cause of the Mexican War might be simply stated in a single word - Texas. The United States wanted Texas, and Mexico did not mean for the Americans to have it. From the moment Texas gained its independence from Mexico in 1836, Mexico blamed the United States for its loss and nurtured hopes for its recapture. …