1861: Confederate forces fire on Fort Sumter in South Carolina, starting the Civil War

1955: Salk’s polio vaccine is declared safe and effective

1961: Soviet cosmonaut Yuri Gagarin orbits the Earth once, becoming the first man to fly in space

1992: $4 billion theme park Euro Disneyland opens in Marne-La-Vallee, France

1999: President Bill Clinton is found in contempt of court for giving “intentionally false” testimony in a lawsuit about his relationship with former White House intern Monica Lewinsky

Source: http://www.nytimes.com