502 – Chinese emperor Xiao Yan names Xiao Tong his heir designate.
640 – Pope John IV is elected.
759 – Tang dynasty poet Du Fu departs for Chengdu, where he is hosted by fellow poet Pei Di.
820 – Emperor Leo V is assassinated in the Hagia Sophia at Constantinople and is succeeded by Michael II.
1144 – The capital of the crusader County of Edessa falls to Imad ad-Din Zengi, the atabeg of Mosul and Aleppo.
1294 – Pope Boniface VIII is elected, replacing St. Celestine V, who had resigned.
1500 – A joint Venetian–Spanish fleet captures the Castle of St. George on the island of Cephalonia.
1777 – Kiritimati, also called Christmas Island, is discovered by James Cook.
1800 – The Plot of the rue Saint-Nicaise fails to kill Napoleon Bonaparte.
1814 – Representatives of Britain and the United States sign the Treaty of Ghent, ending the War of 1812.
1818 – The first performance of "Silent Night" takes place in the church of St. Nikolaus in Oberndorf, Austria.
1826 – The Eggnog Riot at the United States Military Academy begins that night, wrapping up the following morning.
1846 – British acquired Labuan from the Sultanate of Brunei for Great Britain.
1851 – Library of Congress burns.
1865 – The Ku Klux Klan is formed.
1871 – Aida opens in Cairo, Egypt.
1906 – Radio: Reginald Fessenden transmits the first radio broadcast; consisting of a poetry reading, a violin solo, and a speech.
1911 – Lackawanna Cut-Off railway line opens in New Jersey and Pennsylvania.
1913 – The Italian Hall disaster in Calumet, Michigan results in the deaths of 73 Christmas party participants (including 59 children) when someone falsely yells "fire".
1914 – World War I: The "Christmas truce" begins.
1924 – Albania becomes a republic.
1929 – Assassination attempt on Argentine President Hipólito Yrigoyen.
1939 – World War II: Pope Pius XII makes a Christmas Eve appeal for peace.
1941 – World War II: Kuching is conquered by Japanese forces.
1941 – World War II: Benghazi is conquered by British forces.
1942 – World War II: French monarchist, Fernand Bonnier de La Chapelle, assassinates Vichy French Admiral François Darlan in Algiers, Algeria.
1943 – World War II: U.S. General Dwight D. Eisenhower is named Supreme Allied Commander for the Invasion of Normandy.
1945 – Five of nine children become missing after their home in Fayetteville, West Virginia, is burned down.
1951 – Libya becomes independent from Italy. Idris I is proclaimed King of Libya.
1953 – Tangiwai disaster: In New Zealand's North Island, at Tangiwai, a railway bridge is damaged by a lahar and collapses beneath a passenger train, killing 151 people.
1964 – Vietnam War: Viet Cong operatives bomb the Brinks Hotel in Saigon, South Vietnam to demonstrate they can strike an American installation in the heavily guarded capital.
1966 – A Canadair CL-44 chartered by the United States military crashes into a small village in South Vietnam, killing 129.
1968 – Apollo program: The crew of Apollo 8 enters into orbit around the Moon, becoming the first humans to do so. They performed ten lunar orbits and broadcast live TV pictures.
1969 – The oil company Phillips Petroleum made the first oil discovery in the Norwegian sector of North Sea.
1969 – Nigerian troops capture Umuahia, the Biafran capital.
1973 – District of Columbia Home Rule Act is passed, allowing residents of Washington, D.C. to elect their own local government.
1974 – Cyclone Tracy devastates Darwin, Australia.
1980 – Witnesses report the first of several sightings of unexplained lights near RAF Woodbridge, in Rendlesham Forest, Suffolk, England, United Kingdom, an incident called "Britain's Roswell".
1994 – Air France Flight 8969 is hijacked on the ground at Houari Boumediene Airport, Algiers, Algeria. Over the course of three days three passengers are killed, as are all four terrorists.
1997 – The Sid El-Antri massacre in Algeria kills between 50 and 100 people.
1999 – Indian Airlines Flight 814 is hijacked in Indian airspace between Kathmandu, Nepal, and Delhi, India. The aircraft landed at Kandahar in Afghanistan. The incident ended on December 31 with the release of 190 survivors (one passenger is killed).
2003 – The Spanish police thwart an attempt by ETA to detonate 50 kg of explosives at 3:55 p.m. inside Madrid's busy Chamartín Station.
2005 – Chad–Sudan relations: Chad declares a state of war against Sudan following a December 18 attack on Adré, which left about 100 people dead.
2008 – Lord's Resistance Army, a Ugandan rebel group, begins a series of attacks on Democratic Republic of the Congo, massacring more than 400.
