Wikipedia:Selected anniversaries/October 16
- 456 - Magister militum Ricimer defeated Emperor Avitus at Piacenza and became master of the Western Roman Empire.
- 1813 - The Sixth Coalition attacked Napoleon and the First French Empire in the Battle of Leipzig, the largest conflict in the Napoleonic Wars.
- 1843 - William Rowan Hamilton first wrote down the fundamental formula for quaternions on Broom Bridge in Dublin, Ireland.
- 1940 - World War II: Hans Frank established the Warsaw Ghetto, the largest Jewish ghetto in occupied Poland.
- 1978 - Karol Józef Wojtyła, a cardinal from Kraków, Poland, became Pope John Paul II (pictured), the first non-Italian pope since the 16th century and the first ever from a Slavic country.
Recent days: October 15 – October 14 – October 13
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