1: The first Christmas according to calendar-maker and Eastern Roman monk Dionysius Exiguus
800 Pope Leo III crowns Charles the Great (Charlemagne) Holy Roman Emperor

1066: William the Conqueror is crowned King of England at Westminster Abbey, completing the Norman Conquest of England

1741: Astronomer Anders Celsius introduces the Celsius temperature scale, which now bears his name

1868: Despite bitter opposition, US President Andrew Johnson grants an unconditional pardon to all persons involved in the Southern rebellion (Civil War)

1991: Mikhail Gorbachev formally resigns as President of the USSR in a televised speech

Source: Onthisday.com