Bill Gates left the Microsoft board after founding the company four decades prior.
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Itza, the last Mayan kingdom, was conquered by Spanish forces.
Sixteen primary school children and one teacher were killed in a mass shooting in Dunblane, Scotland.
Earmuffs were patented.
The first major revolt of the 1848-1849 German revolutions began in Vienna.
Marvel's 'Captain America: The Winter Soldier' premiered in Los Angeles.
