2014: In the worst massacre of the South Sudanese Civil War, at least 200 civilians were gunned down after seeking refuge in houses of worship as well as hospitals.
2013: Two bombs explode near the finish line at the Boston Marathon in Boston, Massachusetts, killing three people and injuring 264 others.
1989: Hillsborough disaster: A human crush occurs at Hillsborough Stadium, home of Sheffield Wednesday, in the FA Cup Semi-final, resulting in the deaths of 96 Liverpool fans.
1986: The United States launches Operation El Dorado Canyon, its bombing raids against Libyan targets in response to a bombing in West Germany that killed two U.S. servicemen.
1924: Rand McNally publishes its first road atlas.
1923: Insulin becomes generally available for use by people with diabetes.
1922: U.S. Senator John B. Kendrick of Wyoming introduces a resolution calling for an investigation of a secret land deal, which leads to the discovery of the Teapot Dome scandal.
1920: Two security guards are murdered during a robbery in South Braintree, Massachusetts. Anarchists Sacco and Vanzetti would be convicted of and executed for the crime, amid much controversy.
1912: The British passenger liner RMS Titanic sinks in the North Atlantic at 2:20 a.m., two hours and forty minutes after hitting an iceberg. Only 710 of 2,227 passengers and crew on board survive.
1450: Battle of Formigny: Toward the end of the Hundred Years' War, the French attack and nearly annihilate English forces, ending English domination in Northern France.
1395: Timur defeats Tokhtamysh of the Golden Horde at the Battle of the Terek River. The Golden Horde capital city, Sarai, is razed to the ground and Timur installs a puppet ruler on the throne.
1071: Bari, the last Byzantine possession in southern Italy, is surrendered to Robert Guiscard.
769: The Lateran Council condemned the Council of Hieria and anathematized its iconoclastic rulings.