In seeking timeless lessons in the story of President James Polk and his Mexican War, we might best begin by noting that few presidents have been dogged through history by the controversies and passions of their time as has the man who presided over that war. The political emotions that buffeted nearly all the consequential presidents—and Polk certainly belongs in that circle—have long since ebbed as those figures reached the country’s historical pantheon. But Polk and his war decisions are still caught in the maelstrom of controversy. They have generated political opprobrium alongside spirited defenses right up to our own day.

As recently as 2012 we saw the latest major effort to discredit Polk with Amy S. Greenberg’s A Wicked War, which portrayed the U.S. war policy as motivated essentially by racism and national “aggrandizement”—and hence was “contrary to American principles.” On the other side, as long ago as 1947 historian Alfred Hoyt Bill felt a need to defend Polk from such accusations, which swirled around him even then. In Rehearsal for Conflict, he wrote:It has long been our national habit to deplore the War with Mexico as an act of unprovoked aggression … and, while enjoying the full fruits of conquest, to shed crocodile tears over the means by which [the victories] were won,’’ adding that “against this presentation of it more recent historians … appear to have labored in vain.”

This lingering controversy shrouds some fundamental realities of that pivotal time in American history. Given the internal politics of both countries and the geopolitics of the North American continent, it was probably inevitable that Mexico would lose control over lands it had neither the population nor the financial resources to control and that the rambunctious nation to its north would capitalize on that inherent Mexican weakness.

History, after all, is the story of power interrelationships, and power differentials are often at the fulcrum of major events. But a full review of the circumstances and actions leading up to the 1846–1848 war would suggest that America didn’t stomp upon its southern neighbor simply because it could. Indeed, while national aggrandizement certainly figured in the calculus of Polk and most of his countrymen—Manifest Destiny was a powerful cry—the nation nevertheless sought to adhere to its basic principles even as it struggled with the gathering storm clouds that descended upon the continent when the two nations’ interests and sense of honor were thrust into stark conflict.

An understanding of the war requires an understanding of the vast gulf that separated Mexico and the United States in terms of heritage, governance, political habit, social and cultural sensibility, and national success. The United States was, in Ralph Waldo Emerson’s words, “a country of beginnings, of projects, of vast designs and expectations.” Mexico, on the other hand, was a nation struggling to find its footing even 25 years after it gained independence from Spain.

The Anglo-Saxons who descended upon the lands that would become the United States arrived with a resolve to maintain the folkways and mores of their heritage. The men came with their own women and generally didn’t mix with the Native Americans, who were pushed back with brutal disregard to make possible the preservation and expansion of the Anglo-Saxon culture. That culture included concepts eventually codified in the U.S. Constitution, including freedom of speech and conscience, popular sovereignty, governmental checks and balances, a degree of social and political equality, and capitalism. Alexis de Tocqueville, the famous French intellectual, called this document “one of those beautiful creations of human diligence which give their inventors glory and riches but remain sterile in other hands.” He cited as an example of “other hands” Mexico, which he described as a land of “anarchy” and “military despotism.”

While the early British settlers were looking for wealth born of toil, the Spanish came as conquerors and plunderers. They mixed freely with the local populations—Cortes took a lovely mistress in the person of Princess Malintzin, also his interpreter—and pursued riches in the form of gold and rare gems stored away by the leaders of the highly developed civilizations of central Mexico, Peru, and elsewhere. Tragically, those civilizations were quickly destroyed.

Thus, modern Mexico’s bloody emergence brought with it a dual legend—of Tenochtitlan and its fallen heroes on the one hand and of Cortes and his Spanish heritage on the other. This dual legend drove various wedges through Mexican society as it struggled with the intertwined dynamics of race, the Spanish Crown, and the Catholic Church—and then moved toward independence. The elites, both before and after independence, imposed a rigid autocracy to preserve their standing. Commerce was strictly controlled through a powerful mercantilist regimen. And the church embraced this prevailing system, given that the system bestowed upon it vast expanses of property and stores of wealth.

All this ensured that when Mexico won its independence in 1821 it would become a split country beset by crosscurrents of political passion related to ethnicity, autocratic rule, the struggle for governmental stability, and horrendous inequality. The rumbling discontent among the masses was matched by a growing hostility toward the United States, seen as an intrinsic threat. Mexico was correct in seeing this threat, which emanated from disparities in the two nations’ wealth and population. In 1800, total income in the United States was about twice that of Mexico’s; half a century later it was 13 times greater. In 1790, Mexico’s population approached five million compared to fewer than four million in the United States. By 1840, the U.S. population had swelled to 17 million while Mexico’s had reached just seven million.

Indeed, concerns over this population stagnation led Mexico to invite U.S. citizens into Texas to build communities, generate commerce, and create wealth. They came in large numbers but never relinquished their fealty to their own heritage, in contrast to the troubled heritage—and often dysfunctional government—of Mexico. In 1836 these migrants to Texas declared their independence and employed military might to repulse efforts by the Mexican government to bring them to heel. There was plenty of bloodshed, culminating in a de facto state of Texas independence that Mexico never accepted or recognized. But Mexico also lacked the power and resources to do anything about it. Thus did Mexico and Texas enter into an official state of war that lasted a decade, but with no shots fired. Mexico couldn’t retake Texas, which operated as an independent nation, recognized by many countries around the world.

The United States took a cautious approach to this situation on its border. Under President Andrew Jackson, a fervent expansionist, Washington recognized Texas independence, but Jackson made no effort to annex the fledgling nation for fear it would lead to a war with Mexico that could upend his other governmental aims. Martin Van Buren, cautious by instinct, followed Jackson’s lead. But President John Tyler, in the spring of 1844, initiated talks aimed at annexation. It turned out to be wildly popular in the United States, where the idea of westward expansion all the way to the Pacific had stirred powerful national ambitions.

These ambitions would not be thwarted. The annexation initiative was opposed by Henry Clay, the clear favorite for the Whig presidential nomination that year, and by Van Buren, the putative Democratic nominee. Both warned about resulting hostilities with Mexico and also raised concerns about a resurgence of slavery agitation in the country as it sought to absorb likely new territories. Wrote Clay: “Annexation and war with Mexico are identical.” Both politicians saw their ambitions pulverized on the issue. Van Buren lost his party’s nomination in May 1844, and Clay lost his bid for the presidency the following autumn. Polk, who enthusiastically embraced his country’s expansionist impulse, rode the issue into the White House.

When annexation finally came about under Polk’s auspices, Mexico responded with bellicosity, notwithstanding that it had had no control over Texas for nearly a decade. It declared annexation an act of war, withdrew its ambassador from Washington, and threatened to seek redress through force of arms. This was not a surprise to Polk, nor did he particularly lament the Mexican response. That’s because he had a secondary—some would say ulterior—motive in pressing for final annexation. He coveted certain Mexican lands for the United States, beyond the vast Texas expanse. Particularly did he want California, with its enveloping climate, lush agricultural soil, and splendid Pacific harbors at San Francisco and San Diego. In describing this ambition to historian George Bancroft in 1845, the normally sedate Polk had slapped his hand upon his thigh in a rare gesture of enthusiasm.

And he had an ace in his hip pocket—the so-called reparations issue. For years, American citizens attempting to do business in or near Mexico had been abused by Mexican officials and citizens. These abuses included piracy, kidnapping, theft on a grand scale, even murder in a few instances. Some 95 episodes of abuse were recorded by U.S. officials, adding up to millions of dollars in reparation claims. This was no small matter, although anti-Polk historians and commentators tend to dismiss its significance. A reality of international relations is that great nations don’t allow other nations to abuse their citizens with abandon.

Indeed, France actually invaded the Mexican port city of Vera Cruz to secure redress of its own reparations claims. Britain, the global behemoth of the day, threatened similar action to gain payment for its citizens. But the United States took a more measured and peaceful approach, seeking redress through a long series of negotiations with Mexican officials—but to no avail. Preoccupied with internal strife, Mexico generally ignored the American claims. Jackson, in frustration, sent the matter to Congress, suggesting that these “wanton … outrages” and Mexico’s disrespectful response “would justify, in the eyes of all nations, immediate war.” But he added, “We should act with both wisdom and moderation by giving to Mexico one more opportunity to atone for the past, before we take redress into our own hands.”

Long before Polk’s presidency, two congressional committees grappled with the matter. A Senate committee said it could “with justice, recommend an immediate resort to war or reprisals,” while a House panel declared that “ample cause exists for taking redress into our own hands.” But both committees recommended one last effort to secure an appropriate Mexican response.

Although Mexico agreed to talks and a payment schedule was established, regular payments were not forthcoming, and by the time of Polk’s presidency Mexico was still very much in arrears on the matter. Since it was clear Mexico lacked the resources to meet this obligation, Polk devised what he considered a natural way out: the United States would pay the reparation—and add an appropriate financial consideration—in exchange for Mexican territory. He particularly had in mind territory that was sparsely populated since this was land that Mexico couldn’t expect to maintain under its control and since it wouldn’t generate complex cultural frictions and tensions once acquired.

In a hope that Mexico would see merit in such an outcome, Polk entered into a series of diplomatic initiatives aimed at avoiding war while slaking his territorial thirst. He sent an envoy fluent in Spanish to Mexico City to negotiate with Mexican leaders. He told his cabinet he would gladly pay $40 million, along with the outstanding reparations amount, to get the desired territory. But once the envoy arrived, the Mexican leader who had authorized the diplomatic entreaty rejected it, and in any event he was soon deposed—probably because of his willingness to entertain a negotiation with the United States—by a more bellicose military man.  thisissueappears

Polk then entered into an intrigue with a representative of Mexico’s famous General Antonio Lopez de Santa Anna, the former leader who now languished in exile in Cuba. If Polk would foster Santa Anna’s return to Mexico and if he reemerged as the national leader, said the envoy, Santa Anna would negotiate an outcome along the lines of Polk’s desire. The president promptly complied, and Santa Anna did indeed re-emerge as Mexico’s leader, whereupon he quickly reneged on his end of the bargain.

That’s when Polk made a momentous decision. With annexation, the United States inherited a nasty territorial dispute between Texas and Mexico. Texas claimed its territory extended to the Rio Grande, while Mexico insisted the proper border was the Nueces River, far to the east. After all, said Mexico, the Texas boundary, before the war for Texas independence, had never extended into the state of New Mexico, and so no such claim all the way to the Rio Grande could be justified.

Texas countered that it had won all its claimed territory through force of arms, and hence it was the arbiter of its boundary. For 10 years its national legislature had received representatives from the disputed territory (though there was little population there), and Mexico had not maintained any kind of national jurisdiction over the land. Polk argued that in annexing Texas the United States had annexed all territory claimed by Texas. Besides, he wondered how Mexico could make a separate claim upon the disputed territory when it refused to recognize Texas independence at all. The president insisted that the disputed lands were part and parcel of the entire Texas claim, lost to Mexico through the same turn of events that led to what he considered—and America considered—the independent state of Texas.

Under this rationale, Polk on January 13, 1846 ordered General Zachary Taylor to position his army of 3,550 officers and men on the Rio Grande, meaning it would enter and claim jurisdiction over the disputed territory. Taylor built fortifications directly across the river from the little town of Matamoros. He trained his big guns on the town and raised the Stars and Stripes as a band played the “Star-Spangled Banner.” Just a hundred yards away, a 3,000-troop army of Mexican General Francisco Mejia seethed. Soon another 1,600 cavalry soldiers arrived to bolster the Mexican position. It was a tense confrontation, almost guaranteed to generate bloodshed. Taylor sent General William Worth across the river to seek a conference with the U.S. consul at Matamoros. He was refused entry by his Mexican counterpart.

“Has Mexico declared war against the United States?” Worth asked the Mexican general.

“No.”

“Are the two countries still at peace?”

“Yes.”

But it was not a peace that could last, and it didn’t. On April 25, Mexican officers sent a cavalry force of some 1,600 men across the river. It soon encountered an American force of 63 dragoons. A firefight ensued, and 11 U.S. soldiers were killed, six wounded. The Mexican commander took the surviving U.S. contingent captive as prisoners of war.

When Polk heard the news, he knew he had his war. Indeed, even before he got word of the skirmish he was preparing to ask Congress for authorization to go to war with Mexico because of its intransigence on Texas and the reparations issue. Now he had an emotional trigger for his action, and he promptly exploited it. He sent to Congress a message declaring that a state of war existed between the United States and Mexico. He wanted Congress to pass a resolution acknowledging as much, which would be a carte blanche for America to prosecute the war.

Mexico, declared Polk, had “invaded our territory and shed American blood upon the American soil.” Many in Congress were uncomfortable with this narrative, given the disputed nature of the soil involved. As Congressman Garrett Davis of Kentucky put it, “It is our own President who began this war.’’ Most members insisted they would vote to send troops down to protect Taylor’s army from the superior Mexican force facing him, but they didn’t relish a vote on the measure’s “preamble,” which encompassed Polk’s rationale. A leading Senate critic was John C. Calhoun of South Carolina, who waxed eloquent on just what Polk was trying to do. He declared:

I know not whether there is a friend to stand by me … . But here I stand, and stand immovably … . If I could not stand here on a question of truth and veracity, I should be little worthy of the small degree of respect which I am desirous to retain. I cannot vote for this bill without further information, because I will not agree to make war upon Mexico by making war upon the constitution … . As the facts now stand, there is no hostility—no conflict but that between the two armies on the Rio del Norte [Rio Grande]; and yet you affirm … that mere local conflict, not authorized by either government, is a state of war! That every American is an enemy of every Mexican! . . . The doctrine is monstrous.

But Lewis Cass of Michigan argued that events and circumstances at the Rio Grande now dictated war policy, not Polk’s preamble. Taylor faced an overwhelmingly superior force and needed reinforcements immediately, he argued, and any effort to respond merely defensively was destined to fail. The logic of the situation, not Polk, was driving the country to war, said Cass. He thundered on the floor of the Senate:

Are we to confine our efforts to repelling them? Are we to drive them to the border, and then stop our pursuit, and allow them to find a refuge in their own territory? And what then? To collect again to cross our frontier at some other point, and again to renew the same scenes, to be followed by a similar immunity? What sort of a condition of things would this be, sir? The advantage would be altogether on the side of the Mexicans, while the loss would be altogether ours … . No, sir, no vote of mine shall place my country in this situation.

And so the political lines were drawn. When it came time to vote, most members of both houses and both parties found they couldn’t resist the patriotic fervor that had emerged within the electorate, irrespective of how they may have felt about what unleashed the fighting on the Rio Grande. The Senate vote was 40 to 2, with Calhoun refusing to answer the roll call. In the House, the vote was 173 to 14; even Garrett Davis joined the majority.

Polk’s war began with a major miscalculation, however. The president believed it would be a brief conflict. He assumed that a victory or two by Taylor, moving into Mexican territory from the Rio Grande, would induce Mexico to sue for peace. This was unrealistic, as it didn’t take into account sufficiently the pride and patriotism of the Mexican people. As events unfolded, Mexico didn’t win a single battle, yet the country refused to treat with the enemy upon its soil. That led Polk to send another army into Mexico via an amphibious landing at Vera Cruz. Leading that expedition was General Winfield Scott, who had orders to march his army all the way to Mexico City if necessary to force a negotiated settlement. For good measure, Polk sent a State Department official named Nicholas Trist to accompany Scott’s army and serve as negotiator when and if Mexican officials decided to treat.

But they didn’t, and Scott’s army forced its way right into the Mexican capital and planted the American flag upon hallowed governmental buildings there. His military brilliance in doing so was stunning. The Duke of Wellington, probably the world’s most renowned military man at the time, called Scott “the greatest living solder” and added his campaign “was unsurpassed in military annals.” Even then it wasn’t clear that Mexican officials, who had fled the capital, would agree to negotiate an end to the war. That’s when the “all of Mexico” movement began in Washington, as political voices began to agitate for conquering the entire country and attaching it to the United States. Contrary to many historical renditions, including Amy Greenberg’s, Polk never favored such an approach and was in fact uncomfortable with the idea of the United States attempting to absorb such a vast territory with a population far different in cultural, ethnic, and religious identity.

Yet he appeared to have no choice but to order Scott to conquer ever more territory in his now almost desperate effort to force Mexico into a negotiated settlement before growing domestic opposition reached such intensity as to destroy his presidency and the Democratic Party. In the end, that proved unnecessary, as Santa Anna fell from power and was replaced by more realistic members of the Moderado party, who clearly perceived the futility of further warfare against the U.S. military juggernaut. The final settlement, reached at Guadalupe Hidalgo, a few miles north of Mexico City, called for U.S. acquisition of Upper California (excluding what now is known as Baja California) and what is now the American Southwest (present day Nevada, Utah, and Arizona, and parts of New Mexico, Colorado, and Wyoming), as well as the disputed territory between the Rio Grande and Nueces rivers. In exchange, the United States would pay Mexico $15 million and assume reparations payments up to $3.25 million.

Additionally, Mexicans living in the ceded territories would have the choice of staying or leaving, and no tax would be imposed on any property taken by those who decided to leave. After a year, U.S. citizenship would fall to those remaining, unless they stipulated a wish to remain Mexican citizens. Catholic churches in the ceded territory would retain all church property. Indian tribes in the ceded lands would fall to U.S. jurisdiction, and the U.S. would assume responsibility for protecting Mexico from cross-border raids.

It was a signal outcome for the United States, which completed the national push west and established its contiguous territorial outline on the North American continent, with the exception of a small piece of territory in southern Arizona and New Mexico acquired from Mexico in 1853 for $10 million. Adding these vast southwestern lands to the Oregon Territory brought under U.S. control through Polk’s earlier tough-minded negotiation with Great Britain, the 11th president added some 500,000 square miles to the U.S. territorial expanse and created a transcontinental nation facing two oceans and positioned to dominate the globe.

These accomplishments, along with domestic successes in the realm of tariff rates and monetary policy, have cemented a high station for Polk in the various academic polls conducted to assess presidential performance. He consistently has been placed in the “near great” category. Yet the animosities that pursued him in office still gnaw at his reputation. He is demonized as a territorial zealot who lied to the American people in invading a weak and innocent Mexico so he could grab lands as plunder.

Where does the truth lie? Let’s begin with the oft-leveled allegation that he lied to the American people in pressing for his war. It centers largely on his declaration that Mexico had “spilled American blood upon the American soil.” This was, of course, disputed soil, and most experts say the American claim to the disputed land was tenuous at best. Polk biographer Charles Sellers wrote in 1966 that the claim was “indefensible.” Even conceding this point, it doesn’t seem unreasonable that Polk would feel that he had an obligation to treat seriously Texas’s territorial claims. And most presidents would feel an obligation to defend disputed lands pending a negotiated outcome. Why would a president cede such territory without getting something in return, most notably a cessation of Mexican belligerence but also, perhaps, territory elsewhere? Had he allowed Mexico to occupy the disputed lands, it’s likely that history would have condemned such weakness with equal sternness.

On the question of whether Polk lied to the American people, it seems more accurate to say he offered an interpretation of the disputed territory that could be contested, and was contested, by his many adversaries. Mexico said the territory belonged with Mexico; Polk said it had belonged to Texas and hence was now U.S. territory; many others simply accepted the reality that ownership was disputed. It doesn’t seem reasonable that Polk could not put forth his own interpretation without being called a liar.

Polk often has been portrayed as wanting a war with Mexico in order to grab coveted territory. This is not quite true, although there’s no question that he coveted Mexican land and was willing to accept war in order to get it. But his preference was to get it without going to war, as his many efforts at negotiation demonstrate. (This is backed up by numerous entries in his presidential diary.) Indeed, as Polk biographer Eugene Irving McCormac noted in his 1922 study, at one point early in the drama Polk authorized his envoy to assume all reparations claims if Mexico would cede merely the disputed lands between the Rio Grande and Nueces rivers. “Had [the envoy] been able to conclude such a treaty,” wrote McCormac, “Polk would have been deprived of all means of bringing pressure to bear on Mexico, except unprovoked military conquest.” Hence, it seems fair to argue that Polk’s approach was more measured and less belligerent than many of his critics have been willing to acknowledge.

Still, it is indisputable that Polk was not entirely forthcoming to the American people about his aims and what he was willing to do to accomplish them. In this he was not far different from Woodrow Wilson and Franklin Roosevelt, who wanted to nudge their nations into wars for which their countrymen were not ready. And it is also true that Polk’s efforts at negotiation were not always conducted as imaginatively and effectively as they might have been, although it isn’t clear whether that would have made a difference given the wide gap in the outlooks and demands of the two countries.

As for Mexico, it wasn’t precisely the blameless and exploited country often portrayed by Polk’s critics. As Princeton historian Sean Wilentz, one of the leading scholars of the period, has written, “Mexico, far from being a passive, innocent victim of America’s lust for power and land, was ruled by a succession of corrupt, conservative, autocratic and truculent governments that administered a republic in name only, one that was distorted by centuries of domination by the Spanish crown and the Roman Catholic Church.’’ Others have noted that Mexico’s approach to dealing with its powerful neighbor to the north—with defiant belligerence and haughty pride—could hardly have been more unwise or counterproductive, given the power differential between the two nations.

Polk was not a particularly sympathetic figure. He was suspicious, secretive, sanctimonious, manipulative, and not always forthcoming in his dealings with others. He was also a visionary, and he caught the imagination of the American people with his vision of an America stretching from the Atlantic to the Pacific, with fine harbors and ports on both oceans, and with wide rivers and vast expanses of productive fields and forests in between. Clay and Van Buren didn’t share that vision, which is why they were rejected by American voters in 1844 and why Polk emerged as the country’s first dark horse presidential candidate. Far from being a scourge on the American people during his single term in office, he served as an instrument of the people.

Robert W. Merry, longtime Washington journalist and publishing executive, is the author of books on American history and foreign policy, including A Country of Vast Designs: James K. Polk, the Mexican War, and the Conquest of the American Continent.