Grace Kelly married Rainier III, the Prince of Monaco.
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The Treaty of Frankfurt was signed between Holy Roman Emperor Charles V and Protestants.
NASA's Ingenuity helicopter became the first helicopter to fly on another planet.
Prolific killer Charles Manson was sentenced to death by gas chamber.
The Battle of Lexington and Concord began, which kicked off the American Revolutionary War between 1775 & 1783.
Captain James Cook sighted Australia for the first time.
