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

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.

The Lincoln-Douglas debates sharpened the national divide over slavery

In 1858, Abraham Lincoln and Senator Stephen Douglas debated while competing for an Illinois Senate seat. Their seven debates, reprinted nationwide, brought the question of slavery to the forefront—further polarizing the country and propelling Lincoln to national prominence.

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.

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

Abraham Lincoln's victory in 1860 sparked Southern secession—even before his inauguration

Abraham Lincoln's election on an antislavery expansion platform convinced many Southerners that their way of life was under threat. Within three months, seven states seceded from the Union—forming the Confederacy—before Lincoln took office in March 1861.

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.

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.

Truth met President Lincoln at the White House in 1864

In October 1864, Truth traveled to Washington and met President Lincoln a week before his reelection, though she could secure the appointment only through a white abolitionist friend. Lincoln signed her autograph book, and Truth later said she had never been treated with more "kindness and cordiality" by anyone.

A detective foiled an assassination plot against Lincoln before his inauguration

In February 1861, detective Allan Pinkerton uncovered a plot to kill Abraham Lincoln en route to his inauguration. Lincoln secretly altered his travel plans and sneaked into Washington DC to take the oath of office. Pinkerton later founded the well-known Pinkerton's National Detective Agency.

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.

Former American President Abraham Lincoln is one of history’s most famous ghosts

Abraham Lincoln, Anne Boleyn, Pausanias, and the Maharajah Duleep Singh are just a few of the notable phantoms found around the world. Several White House occupants and visitors have claimed to see Lincoln, including Theodore Roosevelt, Grace Coolidge, and Winston Churchill.

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.

Congress's Wade-Davis Bill demanded harsher terms for Southern reentry

Passed in 1864, the Wade-Davis Bill required 50% of white male voters to swear loyalty and guarantee emancipation before readmission. Lincoln pocket-vetoed it, rejecting Congress's stricter approach.

The Lincoln Memorial was almost never built

The Memorial faced years of opposition from Speaker of the House Joseph Gurney Cannon, who blocked it for nearly a decade, arguing that the swampy land west of the Mall was an unfit and undignified site to honor Lincoln.

In the 1930s, Congress nearly passed a constitutional amendment requiring a national vote before declaring war

The Ludlow Amendment, proposed amid rising isolationism after World War I, would have required a national referendum before Congress could declare war, except in cases of direct attack. It was defeated 209 to 188 in 1938 after Roosevelt lobbied against it.

See some of the most controversial pardons in presidential history

From Lincoln's selective commutations of Dakota men after an 1862 uprising, to Ford's pardon of Richard Nixon after Watergate, and Bill Clinton's final-day clemency decisions, pardons have long sparked fierce debate over justice, political favoritism, and presidential power.

Explore early Thanksgiving documents, from recipes to early proclamations

History buffs will love this trove of original documents related to the Pilgrims and Thanksgiving, including 18th-century recipes, one of Sarah Josepha Hale’s appeals to President Lincoln to establish the national holiday, and a copy of Abraham Lincoln’s original 1863 Thanksgiving Day Proclamation. You can also find illustrations and photos of historical Thanksgiving celebrations over the years.

The opposition party to the president first delivered a televised response in 1966

Television networks first granted airtime to the out-of-power party in 1966, with Republicans Everett Dirksen and then-Representative Gerald R. Ford delivering the inaugural response. See a list of each opposition response to the State of the Union since then.

Hamilton's tax on whiskey sparked the first armed rebellion against US federal authority

As Treasury secretary, Alexander Hamilton designed an excise tax on whiskey that provoked violent resistance in western Pennsylvania. The Whiskey Rebellion ended when George Washington mobilized state militias under federal authority to enforce the law.

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 Andrew Johnson was mainly impeached for obstructing Reconstruction

In 1868, the House impeached Andrew Johnson for violating the Tenure of Office Act and obstructing congressional Reconstruction policies. Johnson was the first president ever to be impeached, surviving conviction and removal in the Senate by a single vote.

Explore every War Powers Resolution report submitted to Congress since 1973

This NYU School of Law project catalogs all unclassified 48-hour reports submitted by presidents since the War Powers Resolution was enacted, with search options by president, location, and claimed legal authority.

See how the Declaration evolved from draft to final text

John Adams urged Congress to choose Thomas Jefferson to draft the Declaration because of his literary skill and low-profile reputation. Read Jefferson’s initial draft, which included passages later removed, including a forceful denunciation of slavery.

How Emily Dickinson and Walt Whitman grappled with the American Civil War

Whitman, whose brother was injured while fighting for the Union, was often overt in his pro-Union poems. Dickinson, whose brother paid to have someone enlist under his name, was more subtle, though equally as affected, as this comparative analysis makes clear.

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.

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.

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

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

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

The original copy of the Declaration of Independence is not a pristine document, and even features a smudged anonymous handprint in the bottom left corner.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

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 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.

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

Famed poet TS Eliot rejected the manuscript for George Orwell's political fable 'Animal Farm,' writing that its criticism of authoritarianism was not 'the right point of view.'

The Beatles' US label rejected the band's first two singles, 'Please Please Me' and 'From Me to You,' with one executive calling the band 'dead in the water.'

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

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

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.

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.

70 years ago today, city officials in Santa Cruz, California, banned rock 'n' roll to protect its youth from corruption after witnessing a 'provocative' concert the night before.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.

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

After her fellow cult members tried to kill her with an LSD-infused hamburger, one member of the Manson Family, the murderous cult led by Charles Manson, decided to testify against the group's leader.

Warren Buffett's former professor Benjamin Graham is known as the 'father of value investing,' a strategy in which investors seek to buy stocks trading below their intrinsic worth.

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.

Elk Cloner, the first computer virus to spread in public, was written as a practical joke by Richard Skrenta, a Pittsburgh high school student.

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