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

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.

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.

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 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.

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.

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 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.

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.

New research challenges the myth that Montezuma peacefully surrendered to Spain

For centuries, historians claimed Montezuma II willingly ceded control to the conquistadors, and that later Aztec resistance was a rogue uprising. Evidence now shows no peaceful handover occurred, revealing a far more turbulent and contested encounter between the two warring empires.

The Union victory at Gettysburg marked a major turning point in the war

Fought July 1-3, 1863, the Battle of Gettysburg ended the Confederate invasion of the North. While the Union lost nearly 23,000 troops, its victory in one of America's most famous battles shifted the war's momentum decisively toward the North.

Madison urged Jefferson to accept the Louisiana Purchase despite constitutional concerns

As secretary of state, James Madison helped negotiate the 1803 Louisiana Purchase and persuaded Thomas Jefferson to proceed, arguing that the strategic and economic stakes outweighed the unresolved constitutional questions.

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.

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.

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.

11 states formed the Confederacy, with 2 others claiming allegiance

Between December 1860 and June 1861, 11 Southern states officially seceded to form the Confederacy. Pro-Confederate factions in Missouri and Kentucky also declared secession, but both states remained largely under Union control throughout the war.

The Prize Cases established that the president can respond to an attack without waiting for Congress to act

When Lincoln blockaded Confederate ports at the start of the Civil War without congressional authorization, the Supreme Court upheld his actions, ruling that a president does not initiate war by responding to an attack and need not wait for Congress when the nation is already under threat.

The US finished what the French had started with Panama's canal

For about two decades, Suez Canal-builder and Frenchman Ferdinand de Lesseps led the project, but financial troubles forced it into the hands of the US, who completed it in 1914. This timeline, made to accompany the definitive PBS American Experience documentary about the canal, highlights major moments in its construction.

The diplomat who implemented Monroe's policy introduced the poinsettia to the United States

Joel Roberts Poinsett, appointed as the first US minister to Mexico in 1825 following the doctrine's announcement, took cuttings of a vibrant Mexican plant called the cuetlaxochitl during his time there. Americans loved the foliage and named it after him.

Champagne played a role in resisting the Nazis

When France surrendered to the Nazis in 1940, the invaders occupied the north. This was home to wine regions like Champagne and Bordeaux, which the Nazis were eager to loot. Winemakers took a stand by sheltering dissidents in their cellars, passing intelligence across borders, and even giving their lives to the cause.

The final shots of the Civil War were fired in the Arctic over 2 months after the South's surrender

In June 1865—two months after Lee's surrender—the Confederate raider CSS Shenandoah unknowingly attacked Union whaling ships in the Arctic. When the crew learned the war was over, they sailed 9,000 miles to surrender in Liverpool, England.

Guerilla warfare was a significant part of the success of the Americans

Francis Marion, also known as the Swamp Fox, was a Patriot general who used guerrilla warfare tactics in the Carolinas during the Revolutionary War’s southern campaigns. Also called “maneuver warfare,” the approach focuses on disorienting the enemy and exploiting their weaknesses while avoiding their strengths.

Abraham Lincoln was almost assassinated weeks before his inauguration as he traveled from Illinois to DC through Baltimore in 1861; it took two independent claims for Lincoln to be convinced the threat was real

What were the major battles of the Vietnam War?

As to be expected, there was no shortage of conflict during a war filled with guerrilla tactics. However, there were a few key battles and operations that influenced changes in warfare and ultimately led to the North's victory. This list of key battles starts with conflict between the France and Vietnam and ends with what became known as the fall of Saigon.

Enslaved and in debt: the French roots of Haiti's struggles

This investigative infographic details how Haiti was forced to pay for its freedom twice: once in blood and once in cash. In August 1791, Haiti's enslaved population launched a revolt against French colonists, successfully establishing Haiti as a...

In a 2012 poll, Brits named Washington as the kingdom's greatest military enemy

The poll by the UK's National Army Museum ranked Washington above Irish independence hero Michael Collins, France's Napoleon Bonaparte, German Field Marshal Erwin Rommel, and Mustafa Kemal Atatürk.

Pheasant Island is controlled by both the Spanish and the French

The two-acre plot of land is a condominium—a territory shared by two countries. Pheasant Island (which, curiously, is not home to pheasants) is a holdover from the end of the Thirty Years' War between France and Spain, when it was designated as a neutral area dividing the countries.

Explore an interactive map of battles from the American Revolution, along with detailed summaries of each engagement

The rivalry between Alexander Hamilton and Thomas Jefferson centered on federalism—the question of how much power the federal government should hold relative to the states.

During the French Revolution, a botanist's letter asking about "dear Rhus" (poison ivy) was intercepted, leading authorities to suspect he was conspiring with the Russians.

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

In 1915, workers recovered a submarine-like vessel from the Chicago River, prompting fears of German espionage

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

'Grand Canyon of the Yellowstone,' a work by American painter Thomas Moran, inspired Congress to establish Yellowstone National Park.

The United States has had a tumultuous relationship with Cuba since its 1959 revolution, highlighted by a nuclear crisis and a decades-long trade embargo.

Many legends about George Washington, including his supposed wooden teeth and the story of cutting down the cherry tree, lack evidence.

Quincy Jones' 'Big Band Bossa Nova' helped introduce bossa nova—a jazz-influenced Brazilian genre—to the US

El Niño, Spanish for 'the boy,' was named after Jesus Christ because the phenomenon resembled the weather changes observed around Christmastime.

Learn how monoclonal antibodies, which mimic the body's antibodies, can fight diseases like Ebola.

In 1945, Surrealist artist Salvador Dalí and legendary animator Walt Disney began collaborating on a short film that was not completed until 2003, years after both men had died.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in terms of casualties, forces mobilized, and displacement of civilians.

The story of Dollree Mapp, whose legal challenge over her 1957 conviction for possessing "obscene material" led to a major strengthening of the Fourth Amendment

In 2019, a laptop loaded with six of the worst malware in history and described as 'an exhibit of historical weaponry' sold for $1.3M.

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

In 2025, four executives from large tech companies were given positions in the US Army Reserves—including Palantir Chief Technology Officer Shyam Sankar, which reinforced Palantir's ties with the US military and its role as a leading defense partner.

Brandi Chastain, the star of the 1999 US victory over China in the 1999 Women's World Cup, was a last-second choice to take the penalty kick that sealed the victory.

See how fireworks are made and learn how metals like magnesium and copper are responsible for different colors.