Roman Emperor Valentinian I made his brother, Flavius Valens, his co-emperor.
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The UK issued a new 12-sided £1 coin into circulation.
A nuclear disaster occurred at Three Mile Island in Pennsylvania, US.
An Imperial Airways passenger aircraft crashed in Belgium, killing all fifteen on board.
Frenchman Henri Fabre flew the world's first seaplane in Martinique, France.
The strain of swine flu known as H1N1 had its first case in the US.
