0800 - Charlemagne was crowned first Holy Roman Emperor in Rome by Pope Leo III.
1066 - William the Conqueror was crowned king of England.
1223 - St. Francis of Assisi assembled one of the first Nativity scenes, in Greccio, Italy.
1818 - "Silent Night" was performed for the first time, at the Church of St. Nikolaus in Oberndorff, Austria.
1914 - During World War I, British and German troops observed an unofficial truce and even playing football together on the Western Front.
1926 - Hirohito became the emperor of Japan after the death of his father Emperor Taisho.
1941 - Hong Kong surrendered to the Japanese.
1979 - The USSR invaded Afghanistan in a bid to halt civil war and protect USSR interests.
1989 - Ousted Romanian President Nicolae Ceausescu and his wife, Elena, were executed following a popular uprising.