- The State Department reported that over 40 microphones were found in the US embassy in Moscow. (1964) Embassy workers thought that the embassy had been bugged several years earlier when Stalin had told the embassy that they had to move out, only to tell them to move back in a few weeks later. The discovery did not help US-USSR relations.
- The Dark Day occurred in New England. (1780) A heavy cloud settled over much of New England on this day, causing darkness to fall at 10:30 A.M. The cloud is thought to be a combination of smoke from a forest fire, a heavy fog, and natural cloud cover.
- Mexico ratified the Treaty of Guadalupe Hidalgo. (1848) The treaty ended the Mexican-American war, and Mexico ceded California, Nevada, parts of New Mexico, Utah, Arizona, and Colorado to the US for $15 million US Dollars (USD). The treaty also required Mexico to give up all of its claims to Texas, which had been one of the causes for the war.
- Marilyn Monroe wished President John F. Kennedy happy birthday. (1962) Monroe's now famously sultry rendition of "Happy Birthday" was part of a larger presidential birthday celebration that was taking place in Madison Square Garden in New York.
- The date for the invasion of Normandy was set. (1943) British Prime Minister Winston Churchill and American President Franklin Roosevelt decided that the now-famous invasion of Normandy, also known as D-Day, would take place on 1 May of the following year. The invasion was actually delayed for about a month due to bad weather.
- Oscar Wilde was released from jail. (1897) Wilde had been jailed for homosexuality, and became so weak from starvation while in jail that he fell and burst his eardrum, which contributed to his death. When he was released, he wrote his last work, The Ballad of Reading Jail, and died three years later of meningitis.
- The USSR ratified a treaty banning nuclear weapons in space. (1967) The treaty was one of the first to try to limit the spread of nuclear weapons, and was considered a huge success when the USSR, America's rival in the nuclear arms race, ratified it along with several other European countries and the US.
- The Spanish Armada set off for Britain. (1588) The fleet was considered invincible, and was sailing to try to secure the English Channel to support a Spanish invasion of Britain. The world was shocked several months later when the "invincible" armada was defeated by British forces so badly that most of the ships limped home.
- One of the first species protection measures became law. (1715) New York made it illegal to "gather, rake, take up, or bring to the market" oysters during certain months of the year to help preserve the species. Several similar laws followed in other colonies, including a hunting season on deer in Virginia and a law protecting raccoons in Massachusetts.
- Anne Boleyn was beheaded. (1536) Boleyn was the second wife of Henry VIII, and the mother of the future Queen Elizabeth I. When she failed to produce a son, Henry had her beheaded on charges of adultery, incest, and treason.
