Wikipedia:Selected anniversaries/October 13
- 54 – Claudius was fatally poisoned by his wife Agrippina the Younger, making her 16-year-old son Nero the next Roman Emperor.
- 1773 – French astronomer Charles Messier discovered the Whirlpool Galaxy (pictured), an interacting, grand-design spiral galaxy located at a distance of approximately 23 million light-years in the constellation Canes Venatici.
- 1843 – The Independent Order of B'nai B'rith, the oldest continually-operating Jewish service organization in the world, was founded in New York City.
- 1917 – An estimated 100,000 people in the Cova da Iria fields near Fátima, Portugal witnessed "The Miracle of the Sun".
- 1943 – World War II: With a new government led by General Pietro Badoglio, parts of Italy switched sides to the Allies and declared war on the Axis Powers.
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