It happened on a… April 4

Jack Ma founds Chinese internet company Alibaba.

Kareem Abdul-Jabbar's last NBA game in Seattle.

Wayne Gretzky set an NHL record with his 213th point of the season.

At Cape Canaveral, the space shuttle Challenger took off on its first flight. It was the sixth flight overall for the shuttle program.

Microsoft is founded as a partnership between Bill Gates and Paul Allen to develop and sell BASIC interpreters for the Altair 8800.

Martin Luther King Jr. was assassinated at the age of 39.

The Beatles occupy the top five positions on the Billboard Hot 100 pop chart.

Canada and eleven nations signed a treaty to create The North Atlantic Treaty Organization (NATO).

City of Los Angeles incorporated.

Napoleon abdicates for the first time in favour of his son.