- Massive antiwar demonstrations took place across the US. (1969) Over 100,000 protesters gathered in New York alone, and other demonstrations took place in San Francisco, Los Angeles, and Washington, D.C. Most of the demonstrations were student led, though Quakers also held sit-ins and committed other acts of civil disobedience in more than 30 other cities.
- Darwin sent the first chapters of Origin of Species to his publisher. (1859) Now thought to be one of the most influential books ever published, the Origin of Species laid out Darwin's revolutionary theories of evolutionary biology.
- The hoarding of gold coin and bullion became illegal in the US. (1933) President Franklin Roosevelt signed Executive Order 6102, which ordered people to bring in their gold coins, bullion, and certificates to exchange it for dollars in hopes of boosting the US economy.
- The Battle of the Ice took place on the border of Russia and Estonia. (1242) The battle took place between the Novgorod Republic, a medieval Russian state, and a group of crusaders. It was fought almost entirely on top of a large frozen lake and only ended when the ice collapsed under several thousand soldiers.
- Helen Keller had her breakthrough with the manual alphabet. (1887) Anne Sullivan had been attempting to get Keller to make the connection between objects and words for about a month before she had her breakthrough associating the word "water" with water running across her hand. Keller progressed rapidly after that, and is said to have exhausted Sullivan by running around asking the names of everything she could reach.
- George Washington exercised the first presidential veto. (1792) Washington vetoed a measure that would have provided more seats in the House of Representatives for northern states than for southern states. He only exercised his veto one other time while in office; that was to prevent a reduction in the number of cavalry units in the army.
- Easter Island was discovered. (1722) Dutch explorer Jakob Roggeveen accidentally discovered the island while looking for Australia, two years before Captain Cook's famous expedition reached the island as well. He reported that the island was completely self-sufficient, and mentioned the enormous statues that the island is known for today.
- Pocahontas married John Rolfe. (1614) Pocahontas had served as a go-between for her father's tribe and the English settlers for years, and her marriage ensured peace between the two. Rolfe was an English planter who introduced tobacco to America, and upon marrying him, Pocahontas became "Lady Rebecca."
- Winston Churchill resigned. (1955) Churchill had been suffering from bad health for some years, though he remained in parliament even after resigning as Prime Minister. He is best known for leading Britain through World War II as well as his wit and signature cigars.
- The April Fifth Movement led to violence in Tiananmen Square. (1976) Police, acting on the orders of the Gang of Four, cleared thousands of mourners for the former premier Zhou Enlai of out Tiananmen Square. The incident was later seen as a huge display of patriotism on the part of the mourners after the Gang of Four fell out of power.