US troops committed widespread atrocities during the Mexican-American War

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 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.

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.

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.

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.

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.

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.

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 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.

Japan committed mass war crimes during its invasion of China

During the 1937 invasion, Japanese forces carried out systematic atrocities—including mass executions, rape, torture, forced labor, and chemical warfare. The Nanjing Massacre alone killed tens of thousands over a span of six weeks, with some estimates claiming 300,000.

Was the Mỹ Lai massacre an outlier?

Hundreds of Vietnamese civilians, including children, were tortured and slaughtered during an attack by American troops in what came to be known as the Mỹ Lai massacre. Was such violence as much of an outlier as we’d like to believe? Not according to this researcher’s findings. Author and researcher Nick Turse explains the evidence behind the realization in this 31-minute interview.

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.

The Civil War was the deadliest conflict in American history

Between 1861 and 1865, an estimated 620,000 to 750,000 soldiers died from battle and disease—more than in all other US wars combined.

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."

An overview of drugs, crime, and cartels in Mexico

In 2006, the Mexican government launched a war on the drug cartels. The cartels and the drug trade fuel rampant corruption and violence in Mexico, contributing to tens of thousands of homicides in the country each year. Mexican drug cartels are also...

The US government ran boarding schools designed to erase Native American identity

From the late 19th century into the 20th century, the federal government sent Native children to boarding schools under the philosophy of "kill the Indian, save the man." Children were forbidden from speaking their languages or practicing their cultures, and many endured abuse.

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.

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.

Human sacrifice reinforced Aztec political control and religious belief

The Aztecs controlled a vast territory through military might and intimidation. One very key tactic of control was the ritual of human sacrifice. While an effective scare tactic, the ritual was also grounded in deeply held beliefs that the world was sustained by blood.

The 13th Amendment's criminal exception enabled new forms of forced labor

Southern states exploited the amendment's clause allowing slavery "as punishment for crime" to arrest thousands of Black Americans on minor charges, leasing them to private employers through convict labor systems that persisted for decades.

Why wasn't German emperor Kaiser Wilhelm punished for starting WWI?

The accusations were explosive: a head of state had not only begun an illegal war, but egged his troops on to a series of horrific atrocities that left

Free speech has often been restricted in wartime, potentially unconstitutionally

From the Sedition Act of 1798 to the prosecution of anti-war activists during World War I, the US government repeatedly curtailed speech and dissent during wartime—actions widely criticized and, in some cases, later deemed unconstitutional.

Southern race riots in 1866 galvanized support for more radical Reconstruction

In 1866, white mobs in Memphis and New Orleans killed dozens of Black residents and burned Black neighborhoods. The massacres horrified Northerners, convincing Congress that stronger federal action was needed to protect freedpeople's rights and enforce Reconstruction.

Issues of ICE conduct span multiple Republican and Democratic administrations

Complaints of abuse and harsh treatment increased as detentions and deportations of undocumented immigrants reached record levels during former President Barack Obama's first term. Frontline investigated the causes of these claims in 2011 and found that these issues cross party lines.

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

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

The power and influence of the American presidency have expanded significantly over time—far beyond what the founders envisioned.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

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.

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

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

Mark Twain spent decades feuding with the US Postal Service, convinced its costs and regulations were bureaucratic overreach.

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

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

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

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

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

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.

Georgia O'Keeffe's flower paintings are often assumed to be sexual, though the artist claimed she was simply interested in highlighting the beauty of flowers that most people neglect

View the ten deadliest tornadoes in US history.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

Long before Major League Baseball began allowing instant replay for balls and strikes, an umpire reluctantly used the technology to determine whether a hit was a home run, a move that inadvertently ushered in a new era for the sport.

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

The identity of the Tank Man in the iconic photo from the 1989 Tiananmen Square protests remains unknown and was possibly killed.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

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.

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

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.