0451 - Roman and Barbarian warriors brought Attila's army to a halt at the Catalaunian Plains in eastern France.
1397 - The Union of Kalmar united Denmark, Sweden, and Norway under one monarch.
1756 - In India, 150 British soldiers were imprisoned in a cell that became known as the "Black Hole of Calcutta."
1782 - The U.S. Congress approved the Great Seal of the United States.
1791 - King Louis XVI of France was captured while attempting to flee the country in the so-called Flight to Varennes.
1837 - Queen Victoria ascended the British throne following the death of her uncle, King William IV.
1923 - France announced it would seize the Rhineland to assist Germany in paying its war debts.