Manifest destiny fueled US aggression against Mexico

President Polk deliberately provoked war with Mexico

After Mexico refused to sell California and New Mexico, President James K. Polk ordered US troops into disputed territory between the Nueces River and the Rio Grande—knowing it would likely spark a conflict. When fighting broke out, he used it to justify declaring war.

How the US took half of Mexico

In just two years, the United States redrew the map of North America. Sparked by border disputes in Texas and fueled by President James Polk’s drive for expansion, the Mexican–American War (1846–1848) reshaped both nations.

American annexation of Texas eventually sparked war with Mexico

After Texas won independence from Mexico in 1836, the US annexed it in 1845—despite Mexico’s refusal to recognize Texas as separate. That annexation, combined with a heated border dispute, triggered the Mexican-American War the following year.

Mexico’s political chaos weakened its defense against US invasion

Mexico’s post-independence instability—marked by coups, power struggles, and weak central control—left its northern frontier vulnerable. That political fragmentation shaped Mexico’s unpreparedness during the Mexican-American War and helped enable US conquest.

The Monroe Doctrine helped lead to the American occupation of territory abroad

This podcast explores how the policy motivated a century of US military intervention throughout Latin America, the Caribbean, and the Pacific—covering the annexation of Hawaii, the Spanish-American War, and occupations of Cuba, Haiti, and Panama.

Learn how Mexico’s anti-slavery stance shaped the US–Texas conflict

Historian Alice Baumgartner explores how Mexico’s abolition of slavery clashed with Anglo settlers' ambitions in Texas. The episode reveals how enslaved people fled south to freedom, reshaping the politics that led to Texas independence and the Mexican-American War.

Future President Abraham Lincoln challenged Polk’s justification for war with Mexico

As a freshman congressman, Abraham Lincoln introduced the “Spot Resolutions,” demanding President Polk prove that Mexico had attacked on US soil. This constituted Lincoln’s first major political stand and highlighted growing dissent over the war.

Zachary Taylor became a national hero during the Mexican-American War

General Zachary Taylor led US forces to key victories in northern Mexico, earning widespread fame for his leadership. His popularity from the war propelled him to the presidency in 1848.

US westward expansion—and the status of slavery in the new territories—was a major cause of the American Civil War

The addition of new western lands forced the nation to confront whether slavery would spread beyond the South. Each debate over the admission of a new state sharpened the divide between free and slaveholding regions.

US troops committed widespread atrocities during the Mexican-American War

American volunteer regiments frequently looted towns, raped civilians, and executed prisoners—especially in occupied northern Mexico. Historians have documented how racial hatred and impunity fueled war crimes that were rarely punished by military leadership.

The US won every major battle of the Mexican-American War

Despite being outnumbered in key engagements, US forces defeated Mexican armies across every major front. Superior training, leadership, and logistics allowed the US to win decisively—capturing Mexico City without losing a single major battle.

The Compromise of 1850 tried to settle disputes over land gained from Mexico

Territory acquired in the Mexican-American War reignited fierce debates over slavery’s expansion. The Compromise of 1850 aimed to ease tensions by admitting California as a free state and letting other territories decide the issue—but the compromise ultimately failed and helped pave the way to the Civil War.

Mexico admired Lincoln for opposing the war and supporting Mexican sovereignty

As a congressman, Abraham Lincoln condemned the Mexican-American War as unjust. Years later, as president, he backed Mexico’s fight against French occupation. His principled stance earned enduring respect and monuments across Mexico.

The Roosevelt Corollary transformed the Monroe Doctrine from a defensive warning into a rationale for US military intervention

In 1904, President Theodore Roosevelt declared that the US had the right to exercise international police power in Latin America. Over the following two decades, the US intervened militarily in the region about a dozen times—often enough that Marines became known locally as "State Department troops."

France invaded Mexico to install a puppet monarchy and recover debt

Napoleon III used Mexico's default on foreign loans as cover for a larger imperial ambition: overthrowing President Benito Juárez's government and installing a French-backed monarchy. The Mexican army's surprise victory at Puebla helped delay those plans by nearly a year.

Support for slavery helped drive Texas to revolt against Mexico

Mexico abolished slavery in 1829, but many Anglo-American settlers in Texas brought enslaved people and refused to comply. Their desire to preserve slavery was a major factor in Texas’s 1836 rebellion and independence from Mexico.

The US Army inherited the Apache Wars after the Mexican-American War

The resolution of the Mexican-American War inserted the US Army into an ongoing conflict between Apache groups and outside powers—transforming local resistance into a decades-long struggle against American expansion known as the Apache Wars.

A wave of Latin American independence movements most likely prompted the Monroe Doctrine

Between 1810 and 1822, many Latin American colonies separated from Spanish rule, 10 in the last two years. Concerns that Spain and its European allies might try to regain these republics were a main reason behind Monroe's declaration.

Irish immigrants deserted the US Army to fight for Mexico

During the Mexican-American War, hundreds of Irish Catholic immigrants—facing discrimination in the US Army—defected to Mexico and formed the Saint Patrick’s Battalion. Though many were captured and executed, they remain honored as heroes in Mexico.

See the path Spanish conquistadors took to conquer the Aztecs

Spanish expeditions reached central Mexico as the Aztec Empire was expanding its influence. After securing bases in the Caribbean, they advanced west into Aztec territory, triggering a cascading conflict depicted in this interactive map and timeline.

Explore the social and cultural history of the Mexican-American War

Historian Peter Guardino joins host Don Wildman to explore how the war shaped ordinary lives on both sides of the border. Drawing from The Dead March, the episode reveals how culture, class, and ideology shaped the conflict and its consequences.

Hear the reasoning behind Trump's resurrection of the Monroe Doctrine in 2025

This podcast examines the Monroe Doctrine, from its casual origins in an 1823 congressional update to Trump's "Donroe Doctrine"—highlighting how fears of Chinese influence, concerns over oil prices, and the pursuit of hemispheric dominance influenced the administration's policies toward Latin America.

President Trump invoked the Monroe Doctrine in 2025, announcing a new 'Trump Corollary'

On Dec. 2, 2025, the 202nd anniversary of the doctrine, President Donald Trump issued a proclamation reaffirming US "dominance" in the Western Hemisphere. His administration's national security strategy officially codified the "Trump Corollary," stating that the US would prevent non-hemispheric powers from gaining strategic influence in the Americas.

The Treaty of Guadalupe Hidalgo forced Mexico to surrender over half its territory

Signed in 1848, the Treaty of Guadalupe Hidalgo ended the war but came at a steep cost for Mexico—ceding 55% of its territory, including California and the Southwest, in exchange for $15 million and vague promises to protect Mexican residents.

James Monroe first outlined what became known as the 'Monroe Doctrine' during his 1823 Annual Message to Congress

President Monroe used his Annual Message to Congress to warn European powers against further colonization in the Western Hemisphere, asserting US opposition to foreign intervention and laying the foundation for a cornerstone of American foreign policy that remains to this day.

US military professionalism gave America a decisive edge in the war

The professionalism and engineering expertise of West Point–trained officers—like Grant, Lee, and Meade—gave the US a major advantage in the Mexican-American War, helping them win every major battle.

The Monroe Doctrine was designed to keep Europe out of the Americas

First articulated in 1823 by President James Monroe, the doctrine declared the Western Hemisphere off limits to European colonization. It has since been invoked to justify US military interventions in Latin America, from Teddy Roosevelt's takeover of Venezuela to George H.W. Bush's arrest of Panama's leader Manuel Noriega.

Foreign policy and war defined Madison's presidency

During James Madison's presidency, disputes with Britain and France over trade, maritime rights, and impressment dominated foreign policy, culminating in the War of 1812 and shaping how the United States engaged with major European powers.

Jefferson feared European control in the West of North America

Jefferson pushed for the Louisiana Purchase to prevent France or Spain from dominating the western frontier, securing control of the Mississippi River and vast lands that he felt were essential to America’s strategic and economic future.

The Mexican-American War trained future Civil War generals

Many key military leaders of the Civil War—including Ulysses S. Grant, Robert E. Lee, and Thomas “Stonewall” Jackson—first saw combat in the Mexican-American War, gaining battlefield experience that shaped their later commands.

The British Royal Navy—not the US military—enforced the Monroe Doctrine for most of the 19th century

In the early to mid-1800s, the US lacked the ships and military power to prevent European nations from colonizing the Americas. Britain enforced this to protect its commercial interests by keeping rival European powers out of Latin America.

Some historians claim that Mexico's victory at Puebla may have prevented France from arming the Confederacy

According to some experts, Napoleon III planned to ship weapons from Mexico to Confederate forces to break the Union naval blockade. The delay caused by the Battle of Puebla meant French resources didn't reach the Texas border until after the Union Army's decisive victory at Vicksburg.

One Native leader tried to save his people's land by building a nation

As the US pushed westward in the 19th century, one leader of the Ojibwe people fought back not with arms but with politics, seeking to preserve his people's territory and way of life by building a formal Native nation capable of negotiating on equal footing with the US government.

Why Cinco de Mayo is more popular in the US than Mexico

Many in the United States believe Cinco de Mayo (celebrated annually on May 5) is Mexico's equivalent of the Fourth of July, but that's a common misconception: The holiday commemorates a battle in the fight for independence rather than the day Mexico declared independence. Interestingly, the holiday is more celebrated in the US than in Mexico, largely thanks to the Chicano Movement of the 1960s and 1970s.

How America's cocaine habit fueled its migrant crisis

The United States has been facing a migration crisis along its southern border. Thousands of people have been fleeing their homes in Central America, traveling north through Mexico, and claiming asylum in the USA. Much of this crisis can be traced...

Cinco de Mayo celebrates the Mexican victory at the Battle of Puebla

On May 5, 1862, Mexican forces under General Ignacio Zaragoza repelled a larger, more well-equipped French army at Puebla. The French endured roughly 500 deaths before retreating. Though the French ultimately captured Puebla a year later, the improbable one-day victory became a symbol of national pride.

The Indian Removal Act of 1830 forcibly displaced tens of thousands of Native Americans

Signed by President Andrew Jackson, the act authorized the federal government to negotiate treaties relocating Native nations from their Southeastern homelands to lands west of the Mississippi, often by force.

The Kansas-Nebraska Act sparked violence that foreshadowed the Civil War

The 1854 Kansas-Nebraska Act let settlers vote on whether to allow slavery, repealing the Missouri Compromise. Competing proslavery and antislavery groups poured into Kansas, sparking years of bloody conflict known as "Bleeding Kansas."

The Civil War turned the Continental Divide into an American symbol of identity

Historians argue that the boundary only became a celebrated American symbol in the 1860s, when Civil War-era leaders promoted a west-east geographic divide to replace the devastating north-south political divide, and that the term's use spiked after the transcontinental railroad crossed it in 1868.

US immigrants shifted from primarily originating in Ireland and Germany to Mexico and India

This visualization tracks the top country of birth among US immigrants by state from 1850 to the present, revealing a dramatic shift from European-dominated immigration to today's prominence of Mexican and Indian immigrants.

Mexican Independence Day is celebrated on September 16

Cinco de Mayo is widely mistaken for Mexican Independence Day. September 16 is the actual date, commemorating the 1810 Grito de Dolores, Father Miguel Hidalgo's call to revolution that launched Mexico's war against Spanish colonial rule.

Cinco de Mayo holiday celebrations originated with California's Mexican Americans during the Civil War

California Latinos first celebrated Cinco de Mayo in 1862 through patriotic assemblies called Juntas Patrióticas. Ardent Union supporters, these individuals saw the Puebla victory as a win for democracy against both French imperialism and the Confederate cause.

Was the Civil War really about states' rights?

The Civil War was fought over slavery, and Confederate leaders and supporters admitted as much in the build-up to the war and after. But later on, after the South's defeat, the lie of the Lost Cause was pushed—and it persists to this day. This four-minute video details the story of the Lost Cause, "state's rights", Confederate monuments, and the machinations behind them.

A timeline of US immigration laws

The United States began regulating immigration soon after it won independence from Great Britain, and the laws since enacted have reflected the politics and migrant flows of the times. Here's a timeline of key immigration laws from 1790 to 2014, according to the Pew Research Center.

American archaeology has a complicated legacy

Many national parks were discovered through American archaeological expeditions and, consequently, included the looting of Native American cultural sites and artifacts.

Opposing policies over immigration and sanctuary cities define the contemporary debate over federalism

Disputes between the federal government, Republican-controlled states, and Democratic-controlled cities over immigration enforcement and sanctuary policies have become a central flash point in modern federalism. These conflicts will shape the future of state autonomy, federal authority, and the enforcement of national policy across jurisdictions.

Hollywood helped fund American military activity by boosting bond sales

To help fund its WWI military activity, the US introduced Liberty Bonds—government-issued debt marketed directly to the public. Starting at $50, the campaign targeted working Americans and offered Thrift Stamps to make bond-buying more accessible. Hollywood led the charge, with stars like Charlie Chaplin and Mary Pickford boosting bond sales.

Explore the important legislation that has shaped US immigration policy

Read about pivotal immigration legislation from the 1882 Chinese Exclusion Act—the first law restricting immigration by nationality—through DACA, examining how economic conditions, national security concerns, and social attitudes shaped American immigration policy throughout history.

Day of the Dead has started to blend with Halloween

As American Halloween becomes more popular across the globe, Mexican Day of the Dead celebrations have begun to take on some of its traditions. While some believe this dilutes the holiday, other scholars suggest that Day of the Dead has always been rooted in Catholicism.

World War I brought attention to US reliance on mineral imports

Domestic stockpiles were inadequate for the extended trade disruptions caused by the four-year war. In response, the US Geological Survey increased its geological mapping to help search for important metals alongside new oil fields for fuel.