Born to a middle-class Jewish family that later converted to Lutheranism, Marx trained in law and philosophy before turning to radical journalism and economics. With Friedrich Engels, he wrote the Communist Manifesto and Das Kapital, texts that inspired revolutions and regimes across the globe and made him one of history's most consequential thinkers.

Confined to the volcanic outcrop of St. Helena since 1815, Napoleon spent his final years dictating memoirs and quarreling with his British jailers. He died at age 51, likely from stomach cancer, though rumors of arsenic poisoning persisted for generations. His body was returned to France in 1840 to a hero's burial at Les Invalides.

Facing an empire-building French invasion, roughly 2,000 poorly-armed Mexican troops and irregular cavalry repelled 6,000 French soldiers at the fortified hills of Puebla. Though France later took the city and installed Maximilian I as emperor, the upset victory became a lasting symbol of resistance and national pride, celebrated more enthusiastically in Mexican communities in the United States than in most of Mexico itself.

As part of its unrestricted submarine warfare campaign, the German government placed newspaper notices warning that vessels flying the British flag were liable to destruction in war zones around the British Isles. The warning ran alongside advertisements for the Lusitania's voyage, an eerie juxtaposition that foreshadowed the ship's sinking by a German U-boat just two days later, on May 7, killing 1,198 people.

Meeting in London just four years after the devastation of the Second World War, Belgium, Denmark, France, Ireland, Italy, Luxembourg, the Netherlands, Norway, Sweden, and the United Kingdom signed the founding treaty of the Council of Europe. The organization, distinct from the later European Union, would go on to draft the European Convention on Human Rights and now includes 46 member states stretching from Iceland to Azerbaijan.

Three weeks after Yuri Gagarin's orbital flight stunned the world, NASA launched Alan Shepard atop a Mercury-Redstone rocket for a brief but historic ballistic arc reaching 116 miles in altitude. The flight lasted just over 15 minutes and splashed down in the Atlantic, restoring American confidence in the space race and paving the way for the Mercury program's later orbital missions.