December 25th

President Mikhail Gorbachev resigned following the disintegration of the Soviet Union.
Mikhail Gorbachev
Romanian President Nicolae Ceaușescu and wife Elena were executed. The communist leader and his wife were deposed after a revolution. Their trial lasted for about an hour and then they were summarily executed by a firing squad.
Nicolae Ceaușescu
USSR invades Afghanistan. The airlift of Soviet troops into Afghanistan started a 9 year long war. The anti-Soviet insurgents, the mujahideen, received support from the United States and other western allies.
Soviet–Afghan War
British film actor, director, and producer Charlie Chaplin died in Switzerland at age 88.
Charlie Chaplin
Hirohito becomes the 124th emperor of Japan. Michinomiya Hirohito, known as Emporor Shōwa after his death, becomes the 124th emperor of Japan after the death of his father, Emperor Yoshihito. Hirohito was the Emperor of Japan for 62 years, making him the longest reigning Emperor of Japan.
Despite bitter opposition, US President Andrew Johnson grants unconditional pardon to all persons involved in Southern rebellion (Civil War).
Ulysses S. Grant and the American Civil War
First abdominal surgery performed. American physician Ephraim McDowell became the first person in recorded history to successfully remove an ovarian tumor. He is known as the father of ovariotomy and abdominal surgery. The procedure took about 30 minutes and was performed without any anesthesia.
Ephraim McDowell
George Washington crossed the Delaware River and surprised the Hessians.
George Washington's crossing of the Delaware River
Astronomer Anders Celsius introduces Centigrade temperature scale.
Anders Celsius
Christmas Island discovered. Captain William Mynors on the East India Company ship Royal Mary did not stop at the Australian island, which owes its name to the date of its discovery by Europeans. It was not until 44 years later that the first Europeans stepped on the Island. Sparsely populated, the Indian Ocean island is rich in phosphate, which is mined from the guano – bird droppings.
Christmas Island
Duke William of Normandy ('William the Conqueror) crowned King of England.
William the Conqueror
Pope Leo III crowns Charles the Great (Charlemagne), Roman Emperor.