Irish immigrants deserted the US Army to fight for Mexico

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.

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.

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 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.

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.

Irish music became popular in the US during the 19th century

The influx of Irish immigrants in the mid-1800s, driven by starvation and abysmal employment opportunities, led to a significant Irish-American culture, especially in urban hubs such as New York, Boston, Philadelphia, Chicago, and San Francisco.

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.

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 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.

Manifest destiny fueled US aggression against Mexico

The belief that the United States had a divine right to expand westward—known as manifest destiny—justified President Polk’s push for territorial conquest. It shaped public support for the Mexican-American War and framed the invasion as national destiny.

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.

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.

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.

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.

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

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.

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.

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.

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 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.

Hundreds of women secretly joined the Union and Confederate armies during the war

Hear the story of women who disguised themselves as men to enlist in both Union and Confederate armies—serving as soldiers, medics, and spies.

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.

An Irish soldier recounts the horrors of fighting in World War I

Jack Campbell, who died in 1992, at age 97, served in the British army during World War I with four of his older brothers. Ireland's last "Old Contemptible," Campbell was gassed during the course of the war, and he shares this and other memories on Ireland's 'The Late Late Show' in this 11-minute video.

The Mexican-American War led to the birth of the Associated Press

To cover the distant war efficiently, rival New York newspapers pooled resources to share reports from the front—forming what became the Associated Press. The war marked a turning point in how Americans received real-time news about foreign conflicts.

Hughes reported on Black Americans volunteering in the Spanish Civil War

In 1937, the Baltimore Afro-American newspaper sent him to cover the Black soldiers who’d left the US to fight in the International Brigades cooperating with the Republicans in the Spanish Civil War. Hughes’ dispatches mainly focused on the racially integrated military companies, something that was prohibited in the US.

The southbound Underground Railroad: finding freedom in Mexico

Until recently, the southbound Underground Railroad, as some scholars call it, has been largely overlooked, mainly because it left so few traces in surviving records. Read this article to learn more about this dangerous path and its travelers.

In 2013, consumers reportedly purchased more beer on Cinco de Mayo than on Super Bowl Sunday or St. Patrick's Day

Beginning in the early 1980s, breweries positioned Cinco de Mayo as a "Mexican St. Patrick's Day," sponsoring events and targeting Latino consumers. Anheuser-Busch and Miller created Hispanic marketing departments, while Coors spent over $60 million marketing to Latino consumers.

The Chicano movement revived Cinco de Mayo as a symbol of resistance in the 1960s

After decades of little relevance, Chicano civil rights activists on campuses across the Southwest reclaimed the holiday in the late 1960s. Members of the movement described it as a declaration of cultural pride and self-determination

France, Spain, and Britain formed a joint military alliance to force Mexico to repay its debts

In October 1861, the three powers signed the Convention of London and landed troops at Veracruz that December. Britain and Spain reached settlements with Mexico and withdrew. France refused and aimed to change the regime in power in Mexico.

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.

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.

Approximately 180,000 African Americans served in Union forces

About 180,000 Black soldiers—roughly 10% of the Union army—served in the United States Colored Troops after 1863. Despite lower pay and discrimination, they were crucial to the Union victory.

Chicano artists shaped the celebration of Day of the Dead in the US

Beginning in the 1970s, Mexican-American artists have used Day of the Dead components like ofrendas and festivals to combine cultural identity with social justice movements, highlighting indigenous traditions to address issues like gang violence.

Thoreau's 'Civil Disobedience' was largely a protest against the Mexican-American War

Henry David Thoreau refused to pay taxes that funded what he saw as an unjust war waged to expand slavery. His act of protest inspired his famous essay "Civil Disobedience," a foundational text for nonviolent resistance.

...and allowed newly arrived European immigrants to maintain their cultures

19th-century public schools often included Protestant spiritual instruction, something that was disturbing for Catholic immigrants from Ireland, Italy, Poland, and elsewhere, who found homes in neighborhood “parochial” schools.

Yellow fever sidelined more US troops than enemy fire during the Spanish-American War

The disease, transmitted by the Aedes aegypti mosquito, sickened more than 2,000 soldiers. Fewer than 400 American soldiers died in the 1898 war.

Twain served in a Confederate militia for two weeks

In 1861, a 25-year-old Twain joined the Marion Rangers, a pro-Confederate militia. The group disbanded after two weeks upon hearing that Ulysses S. Grant, General of the Union Army, was headed their way. Twain moved to Nevada, where he eventually took a job at a newspaper.

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.

Native students fought back against forced assimilation at US boarding schools

Despite harsh conditions, Native American students preserved their identities by secretly speaking their languages, maintaining cultural practices, and, in some cases, running away.

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...

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.

The Harlem Hellfighters, WWI's longest-serving US regiment

The nickname was given to the 369th Infantry Regiment, an all-Black fighting force of Americans attached to the French Army during World War I. The group fought for 191 days, longer than any other regiment in the United States Army, and lost more men (1,500) than any other.

The US Army massacred close to 300 Lakota men, women, and children at Wounded Knee in 1890

Fearing the Ghost Dance—a spiritual movement spreading across starving reservations—the Army surrounded a Lakota encampment at Wounded Knee Creek, South Dakota. When a shot was fired during an attempted disarmament, it sparked chaos, and soldiers killed nearly 300 people.

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.

Grosse Île, the quarantine island of the Port of Quebec

As tens of thousands of Irish emigrated to North America to escape the Great Famine in the mid-19th century, many port cities set up quarantine areas amid an epidemic of cholera. In Quebec City on the St. Lawrence River, one island became a mass graveyard where over 3,000 Irish immigrants died over a decade as they waited in quarantine. Listen to the history here.

Since the revolution, approximately 1.4 million Cubans have fled to the US

Although Castro initially enjoyed broad support after toppling Batista in 1959, nearly 2 million Cubans chose exile in the years that followed. Most settled in the US, while others dispersed across Latin America and Europe, shaping migration patterns that persist to this day

How the US entered WWI in 1917

Originally taking a position of neutrality during the course of World War I, the United States of America eventually relented. Entering the war in 1917, support for the British and French had risen and Americans were incensed by Germany's overtures to Mexico and U-boat attacks that sank ships and ended American lives. See how and why the US entered WWI in this article.

Shays' rebellion pitted rebel veterans against the Revolution's leaders

The Revolutionary War led to independence and significant debt for most states. In 1786, a group of veterans and farmers from western Massachusetts protested against the state government’s increased taxes. Led by Daniel Shays, the group attempted to capture an armory in Springfield but failed.

Puebla holds an annual battle reenactment on Cinco de Mayo

Each May 5, the city of Puebla marks the anniversary with festivals and a full military reenactment of the 1862 battle. While Cinco de Mayo is barely observed elsewhere in Mexico, it remains a ceremonial source of local pride in the state where the battle was actually fought.