October 16: World Food Day.

• 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 with over 500,000 troops involved.

• 1843 – William Rowan Hamilton (pictured) first wrote down the fundamental formula for quaternions, carving the equation into the side of Broom Bridge in Cabra, Dublin, Ireland.

• 1940 – World War II: Nazi Governor-General 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, the first non-Italian pope since the 16th century and the first ever from a Slavic country.

More events on this day... Recent days: October 15 – October 14 – October 13