The US-Mexican border transects 1,954 miles of mountainous desert terrain from the Pacific Ocean to the Gulf of Mexico, following the course of the Rio Grande for two-thirds of its length. It is the world’s busiest international boundary, with millions of people and billions of dollars in commodities crossing both ways each year.

The border has been in the news of late, with drones, Marines, and racist vigilantes mobilized to stop an alleged “invasion” by “hordes” of “terrorists,” “criminals,” and “rapists.” In the increasingly xenophobic culture war, undocumented immigrants are being scapegoated for American capitalism’s accelerating decline. Trump has accused immigrants of “poisoning the blood of our country.”

Never mind that the overwhelming majority of those who risk their lives to enter the US without papers do so out of economic necessity, chased from their homes by the poverty and instability inflicted on their native lands by imperialism. Or that corporate America reaps enormous profits by exploiting their labor, without which the economy and national treasury would be in even direr straits.

So, where did the border come from? While most people take it for granted, it hasn’t always existed. In fact, the current boundary was only finalized with the Chamizal Convention of 1963. Although geography certainly plays a role, in the final analysis, all political borders are fluid and artificial and merely reflect the balance of class, economic, and military forces at any given time.

If the workers of North America are to overcome this particularly divisive demarcation, we must understand its origins in the Mexican-American War of 1846–48.

Following decades of aggressive westward expansion and genocidal wars against Indigenous peoples, the war marked a new stage in the American ruling class’s relentless drive to dominate the continent. Impelled by the mythology of Manifest Destiny, they embarked on one of the biggest land grabs in human history.

However, not everyone was keen on transforming the American republic into a de facto empire through a predatory war. Abraham Lincoln was a vocal critic, and his fledgling congressional career was derailed as a result. Future Civil War hero and president, Ulysses S. Grant, considered it “wicked” and “the most unjust war ever waged by a stronger against a weaker nation … an instance of a republic following the bad example of European monarchies.” And as Ralph Waldo Emerson prophetically warned, “Mexico will poison us.”

Once the hostilities were concluded, differences over how the conquered territories should be administered intensified the already frenzied national debate over slavery. This deepened the sectional divide and contributed to the collapse of the Second Party System, long dominated by the Whigs and Democrats. Eventually, the intractable differences gave rise to the Republican Party, Lincoln’s election in 1860, the secession of 11 states, and the American Civil War.

Despite its historically progressive character, however, the Second American Revolution was national-democratic in nature, and far from abolishing the nation-state and its borders, it entrenched them even further. The US-Mexico border remains a festering wound that can only be healed through a socialist revolution waged by the united working class across both sides of the divide.

Colonial America

If and when Americans think of their country’s colonial past, they most likely envision English settlers huddled along the Eastern seaboard. Massachusetts and Virginia—not Texas and California—are considered by most to be the “birthplace” of America.

However, the British were not the only Europeans who invaded the Americas. In 1493, Pope Alexander VI divided the Western Hemisphere between Spain and Portugal. Spain was allotted 16 million square miles—80 times the size of the mother country. These lands were inhabited by tens of millions of people, most of whom died in the most horrific genocide in human history.

Therefore, the Spaniards who entered the Sonoran Desert in the 1540s were the first Europeans to enter lands that would eventually be part of the USA. Long before the Mayflower set sail from England, Spain had established permanent settlements in Florida and New Mexico and short-lived colonies in Virginia and Georgia. Spanish explorers had been everywhere from the Oregon coast to the Canadian Maritimes and the Caribbean.

St. Augustine, Florida, was founded in 1565, predating Jamestown by over 40 years. Santa Fe’s Palace of the Governors, built in 1610, is the oldest public building in the US. The Spanish also founded dozens of missions—including San Antonio, San Francisco, San Diego, and Tucson—most of them run like mini slave colonies.

But Spain was embroiled in endless wars of religion and succession in Europe, and tight control over these extensive lands and peoples was impossible. Not only did the British and other powers gain toeholds in North America, but Spain’s holdings in the arid American Southwest and Northern Mexico were sparsely populated and economically and politically neglected. As a result, the region was culturally and geographically distinct from the more tropical, semi-feudal heartland of Mexico’s central plateau.

After a decade of heroic revolutionary struggle, Mexico gained independence from Spain with the Treaty of Córdoba in 1821. However, its economy was in ruins, and the central state was extremely weak. The scale of the political chaos that followed is starkly illustrated by the fact that between 1821 and 1855, Mexico’s presidency changed hands 50 times.

 

Despite successfully fending off Spanish efforts at reconquest in the 1820s and a French invasion in 1838, separatist movements in far-flung regions like Yucatán and East Texas gained traction, while the Comanche carved out a virtual steppe empire spanning from New Mexico to Kansas.

Intrigues, plots, and corruption were pervasive. Like jackals circling a wounded animal, the Americans, British, and French had their eyes on Mexico’s rich pickings, the Monroe Doctrine notwithstanding. Tensions between the Americans and the British were also rising over the Oregon Territory. It was in this context that Texas declared its independence from Mexico.

The “Texas Revolution”

In 1822, hoping to hold back the Comanche, Mexico opened its sprawling province of Tejas to American settlement—but only if the immigrants learned Spanish and respected the country’s laws. But instead of risking life and limb on the llano estacado of West Texas, most Americans homesteaded closer to the Louisiana border in the East. Few of them learned Spanish or respected the law, and many brought their chattel slaves with them.

By 1829, Mexico perceived this concentration of American power within its borders as a threat. To cut across it, it closed the province to further immigration, banned slavery, reinstated property taxes, and increased tariffs on American goods. To resolve the issue, President Andrew Jackson offered to buy Texas for $5 million, but the Mexicans flatly refused.

However, the Mexican government was too weak to enforce its laws, and by 1835, 30,000 Americans lived in Tejas, outnumbering residents of Spanish descent by a ratio of six to one. On October 2 of that year, Mexican troops were sent to the settlement of Gonzales to recover a cannon lent to the American colonists to defend against Indian attacks. After the Americans dared the Mexicans to “come and take it,” a skirmish broke out. The so-called “Texas Revolution” had started. In reality, it was a slaveowners’ rebellion presaging the secession of the Confederacy and a further step toward American domination of the continent.

A series of battles ensued, including the fabled siege of the Alamo and the Goliad Massacre, in which Mexican troops executed some 400 Texan prisoners. On March 2, 1836, Texas declared its independence from the government of Antonio López de Santa Anna, and Sam Houston was appointed commander-in-chief of the Texan forces.

On April 21, Houston defeated Santa Anna’s army at the Battle of San Jacinto, and the Mexican president was captured. While a prisoner of war, he signed the Treaties of Velasco and agreed to recognize the secession of Texas. The “Lone Star” state was recognized as an independent republic by the US and other powers.

However, the Mexican Congress refused to ratify the terms, as Santa Anna had signed them under duress. As a result, the formal status of Texas and its borders remained unresolved. According to Mexico, the province of Tejas’s southern border was the Rio Nueces. According to the Texans, the border was 150 miles south, at the Rio Bravo del Norte—known in the US as the Rio Grande.

Both sides committed cross-border raids and atrocities as the Mexicans tried on several occasions to bring the Texans to heel. Jingoist American papers like the New York Herald only reported one side of the story, decrying the “rapacious and bloody Spaniard” to whip up support for US intervention and annexation:

The Anglo Saxon race is intended by an overruling Providence to carry the principles of liberty, the refinements of civilization, and the advantages of the mechanic arts through every land, even those now barbarous. The prostrate savage and the benighted heathen, shall yet be imbued with Anglo Saxon intelligence and culture, and be blessed with the institutions, both civil and religious, which are now our inheritance. Mexico, too, must submit to the o’erpowering influence of the Anglo Saxon.

A pretext for war

Many in the US favored annexing Texas immediately. However, the delicate balance of federal power between free and slave states precluded this—for the time being.

As the years passed, Mexico remained embroiled in dysfunctional turmoil, whereas the US economy boomed and the industrial revolution gathered steam. Despite encompassing a much larger territory at the time, Mexico’s population was a mere eight million, compared to 22 million in the US.

But the Southern states felt increasingly threatened by the North’s rising economic power. Many saw Mexico and the Caribbean as the solution. They salivated at the thought of a sprawling slave empire that would dwarf their rivals above the Mason-Dixon line. As far as future Confederate president Jefferson Davis was concerned, the Gulf of Mexico should be “a basin of water belonging to the United States,” and “the cape of Yucatan and the island of Cuba must be ours.”

In 1842, the US Ambassador, Waddy Thompson Jr., suggested Mexico might cede Alta California to settle its debts, calling it “the richest, most beautiful, and healthiest country in the world.”

In the 1844 election, Democratic Party slaveowner James K. Polk defeated the Whig candidate, Henry Clay, in a referendum on annexing Texas, California, and if push came to shove, going to war with Britain over the Oregon Territory. Mexico was an obstacle to Manifest Destiny, and Polk was its personification.

However, there was healthy opposition to starting an unprovoked war, particularly in Yankee New England and the free-soil Midwest. Polk sent a diplomatic mission to Mexico with an offer to buy Texas, California, and everything between for $25 million. Once again, Mexico refused the offer.

So, the US upped the ante. On December 29, 1845, it admitted Texas as the 28th state in the union. Mexico, which had never recognized the Texas Republic, responded by cutting off all diplomatic ties with the US. To seal the deal, Polk and his cabal turned to a time-honored trick to provide moral cover for military aggression.

General Zachary Taylor, better known as “Old Rough and Ready,” was sent with a contingent of US troops to occupy the lands between the Nueces and Bravo Rivers, territory clearly belonging to Mexico but claimed by Texas. On April 25, 1846, a patrol of American dragoons, led by Captain Seth Thornton, was ambushed by Mexican cavalry, with 11 killed and 46 captured. The “Thornton Affair” gave Polk the excuse he was looking for.

On May 11, he addressed Congress and presented them with a “war in being,” cynically declaring that “Mexico has passed the boundary of the United States, has invaded our territory and shed American blood upon American soil.”

Never mind that Mexico never declared war on the US, and no Mexican soldier ever set foot on what was actually American soil. Ulysses S. Grant, who fought in the war, later wrote in his memoirs, “We were sent to provoke a fight, but it was essential that Mexico should commence it.” And as Henry Clay declared, “This is no war of defense, but one of unnecessary and offensive aggression.”

On May 13, 1846, Congress officially declared war on Mexico. General Taylor proceeded to blockade the mouth of the Rio Grande and built “Fort Texas,” overlooking the Mexican city of Matamoros. The stage was set for the eventual conquest of half of Mexico’s land.

The forces of war

Mexico is a vast country, and before the expansion of the railroads, only human and animal power was available to move supplies across its harsh terrain. Communication was also an issue, as it could take up to two months for a message from Mexico City to get to Washington and back.

Despite the weakness of the Mexican government, its military was relatively tough after decades of revolution, wars, and uprisings. It outnumbered the Americans by a significant margin, and its cavalry was counted among the best in the world. Although the Mexicans clearly lost the war, they won a handful of minor battles and stopped several amphibious landings. By no means were Polk’s invaders guaranteed victory.

However, the political vacuum and constant chaos in the capital undermined the Mexicans at every turn. The political backstabbing, spies, treachery, and treason, including a plot to restore the Spanish monarchy, all took their toll. The Catholic Church sided with Polk and the Americans and incited a major rebellion, arguing the US incursion was God’s punishment for the sin of taxing the Church’s wealth.

Regional declarations of independence by Tabasco and Yucatán didn’t help stabilize the situation. Incredibly, only eight states supported the central government’s efforts to resist the US invasion. Top officials in Guanajuato wanted the entire country to be annexed by the US. To put it mildly, 1846 was a rough year for Mexico, and it’s a miracle the country survived.

As for the Americans, despite being outnumbered, their regular troops were better organized, disciplined, and commanded than their Mexican counterparts. Their ranks also included thousands of short-term volunteers and irregular militia like the Texas Rangers. Not all of them were orderly, and most were out for plunder and land of their own. Even the “pacifist” Mormons got in on the action after God told Brigham Young that this was a just war. Their reward was the state of Utah. And while many Americans raped, hanged, and beheaded Mexican civilians, others married local women and settled in the country after the war.

The US held a clear advantage when it came to field artillery. Its guns were light and mobile, had greater range, and fired a wide variety of shot. Mexican cannons and tactics were old and cumbersome by comparison. Although the Americans had access to some modern rifles and pistols, for the most part, both armies were equipped with smoothbore flintlock muskets. These were so ineffective that according to U.S. Grant, “a man might fire at you all day without your finding it out.”

Polk planned to occupy territory in Northern Mexico to force a negotiated settlement. But the Mexicans refused to give up without a fight, so he was compelled to send an army to take the capital. However, other than the symbolic political center, a few key ports, and rail junctions, the Americans never fully conquered or occupied the entirety of their southern neighbor.

Much myth and legend has been written about the war on both sides. For example, when teenage Mexican military cadets defended the Castillo de Chapultepec in the heart of Mexico City, it is alleged that one of these “Niños Héroes,“ Juan Escutia, leaped from the ramparts wrapped in the Mexican flag to prevent its capture by the Americans.

Whether this specific episode happened or not, there were countless documented examples of military daring and individual heroism by both US and Mexican soldiers. But the honor goes, above all, to the ordinary Mexican people, thousands of whom died tenaciously defending their cities and neighborhoods in bitter house-to-house fighting despite being armed only with primitive weapons, stones, and roofing tiles.

The course of the war

The war unfolded chaotically, with three American armies leading three prongs of attack over 21 months: from Texas into Northern Mexico, west across New Mexico to California, and a march on Mexico City via Vera Cruz.

The first army was Zachary Taylor’s, which had provoked the war in the first place. In the Spring of 1846, after being reinforced and breaking out of the Mexican siege of “Fort Texas,” Taylor’s troops defeated the Mexicans at Palo Alto and Resaca de la Palma, leading to the capture of Matamoros. By September, his army had reached the city of Monterrey, which was only taken after several days of bloody urban combat.

Meanwhile, in June 1846, Colonel Stephen W. Kearny led the Army of the West from Fort Leavenworth with approximately 1,700 men, including cavalry and artillery units. Despite having 4,000 armed men at his disposal, New Mexico’s governor retreated without offering resistance, and Kearny took Santa Fe without firing a shot. He established a civil government and proclaimed New Mexico’s inhabitants to be US citizens.

At the same time, a group of American settlers in Sonoma launched the “Bear Flag Revolt” and declared an independent “California Republic” after a night of heavy drinking. The new nation lasted just 25 days when American Commodore John D. Stockton of the Pacific Squadron arrived and claimed California for his country. He was joined by Colonel Kearny and 100 mounted dragoons, who helped secure the new territory.

Back in Mexico City, after months of political upheaval, Santa Anna was again president of Mexico—a post he would fill 11 times. After raising an army of 15,000, he headed north to confront Taylor’s army of 4,500, but was repelled at Buena Vista. Threatened by Taylor’s rising popularity, President Polk recalled him and put General Winfield Scott in command of the final phase of the war: the landing at Vera Cruz and the march on Mexico City.

Scott is considered by many to have been the finest soldier ever produced by the US. It was he who conceived the “Anaconda Plan” that successfully strangled the Confederacy during the Civil War. The Duke of Wellington considered Scott “the greatest living soldier” and his exploits in Mexico “unsurpassed in military annals.” For his part, Scott viewed himself as the second coming of Cortez. American soldiers were even given books detailing the history of the Spanish conquest of the Aztecs, and they followed essentially the same route to Mexico City.

But the reality is that war means suffering, cruelty, and death, and Scott’s legacy is far more complicated. For example, in March 1847, after a weeks-long blockade, the port of Vera Cruz was hit with over 6,000 cannon rounds, many of which fell on homes, schools, and churches. Scott had given the women and children two hours to evacuate, which they refused. When the bombardment began, they appealed to Scott to be allowed to leave after all, but he refused until they surrendered unconditionally. The bombing continued. Out of the 3,000 Mexicans who defended the city against 12,000 Americans, 2,000 were killed, including 1,600 civilians, and the city was set on fire.

In April 1847, after several engagements en route to Mexico City, Scott’s forces defeated yet another army raised by Santa Anna at Cerro Gordo, opening the road to the capital.

Finally, after a series of battles to control Mexico City, including Molino del Rey and Chapultepec, Scott and his troops marched into the ancient zócalo and flew the Stars and Stripes above the historic plaza.

Aftermath and legacy

Under the terms of the Treaty of Guadalupe Hidalgo, signed on February 2, 1848, Mexico was forced to recognize the US annexation of Texas, with its border at the Rio Grande. It was also forced to cede around half of its territory, including the modern-day states of California, Nevada, Utah, Arizona, New Mexico, Colorado, and Wyoming, along with chunks of Kansas, Oklahoma, and Texas. As far as those residents with deep roots in the region are concerned, “we didn’t cross the border—the border crossed us.”

In return, the US paid Mexico $15 million and assumed $3.25 million in debts owed to American citizens. Polk wanted even more land, but his peace envoy, Nicholas Trist, negotiated less onerous terms because of the unjustness of the situation.

All told, an estimated 25,000 Mexicans and 13,283 Americans died during the conflict, most of them from disease, in what was the highest mortality rate of any war in US history.

The war was also a training ground for West Point’s “Class of 1846,” with many officers who fought in it going on to serve on both sides in the Civil War. From U.S. Grant, William T. Sherman, and George Meade on the Union side to Robert E. Lee, James Longstreet, and Thomas “Stonewall” Jackson for the Confederates, Mexico was a rite of passage and an opportunity to hone the art of war.

The year 1848 was momentous, with a wave of revolutions across Europe and the publication of the Communist Manifesto. That same year, General Zachary Taylor translated his wartime fame into a successful run for the presidency as the Whig Party candidate in an election dominated by the question of slavery and the territories taken from Mexico. Shortly after presiding over the Compromise of 1850, a cobbled-together arrangement that kept the Civil War at bay for a few more years, Taylor died of cholera just 16 months into his term.

With the 1853 Gadsden Purchase of lands in southern Arizona and New Mexico, the main contours of the current US-Mexico border were defined.

However, US imperialism was only getting started, and many more imperialist crimes lay in its future, including the Philippines, Cuba, Puerto Rico, Korea, Vietnam, Afghanistan, and Iraq. The US was, after all, in the words of Ralph Waldo Emerson, “a country of vast designs.”

After decades of wreaking havoc around the planet, US imperialism has peaked and is now in the midst of a precipitous decline. The internal and external convulsions of this process are reverberating worldwide. In one country after another, the compounding economic, social, and political crises will eventually lead to an all-out revolutionary crisis.

Like wildfires, wildlife, and millions of humans driven by desperate necessity, revolutions do not respect borders. It falls to the current generation and the socialist revolution to abolish all artificial borders and build a Socialist Federation of the Americas as a component part of a World Socialist Federation.