The UK issued a new 12-sided £1 coin into circulation.
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The strain of swine flu known as H1N1 had its first case in the US.
Roman Emperor Valentinian I made his brother, Flavius Valens, his co-emperor.
The Vienna Philharmonic Orchestra performed its first concert.
The European Union Parliament declared single-use plastics were to be banned by 2021.
Frenchman Henri Fabre flew the world's first seaplane in Martinique, France.
