December 11 is the 345th day of the year (346th in leap years) in the Gregorian calendar; 20 days remain until the end of the year.
220 – Emperor Xian of Han is forced to abdicate the throne by Cao Cao's son Cao Pi, ending the Han dynasty.
361 – Julian enters Constantinople as sole Roman Emperor.
969 – Byzantine Emperor Nikephoros II Phokas is assassinated by his wife Theophano and her lover, the later Emperor John I Tzimiskes.
1041 – Michael V, adoptive son of Empress Zoë of Byzantium, is proclaimed emperor of the Eastern Roman Empire 1239 – Treaty of Benavente: the heiresses of the Kingdom of León renounce their throne to King Ferdinand III of Castile 1282 – Battle of Orewin Bridge: Llywelyn ap Gruffudd, the last native Prince of Wales, is killed at Cilmeri near Builth Wells in mid-Wales.
1602 – A surprise attack by forces under the command of Charles Emmanuel I, Duke of Savoy, and his brotherin- law, Philip III of Spain, is repelled by the citizens of Geneva.
1640 – The Root and Branch petition, signed by 15,000 Londoners calling for the abolition of the episcopacy, is presented to the Long Parliament.
1688 – Glorious Revolution: James II of England, while trying to flee to France, throws the Great Seal of the Realm into the River Thames.
1792 – French Revolution: King Louis XVI of France is put on trial for treason by the National Convention.
1815 – The U.S. Senate creates a select committee on finance and a uniform national currency, predecessor of the United States Senate Committee on Finance.
1816 – Indiana becomes the 19th U.S. state.
1899 – Second Boer War: In the Battle of Magersfontein the Boers commanded by general Piet Cronjé inflict a defeat on the forces of the British Empire commanded by Lord Methuen trying to relieve the Siege of Kimberley.
1901 – Guglielmo Marconi transmits the first transatlantic radio signal from Poldhu, Cornwall, England to Saint John's, Newfoundland.
1905 – A workers' uprising occurs in Kyiv, Ukraine (then part of the Russian Empire), and establishes the Shuliavka Republic.
1907 – The New Zealand Parliament Buildings are almost completely destroyed by fire.
1913 – More than two years after it was stolen from the Louvre, Leonardo da Vinci's painting Mona Lisa is recovered in Florence, Italy. The thief, Vincenzo Peruggia, is immediately arrested.
1917 – World War I: British General Edmund Allenby enters Jerusalem on foot and declares martial law.
1920 – Irish War of Independence: In retaliation for a recent IRA ambush, British forces burn and loot numerous buildings in Cork city. Many civilians report being beaten, shot at, robbed and verbally abused by British forces.
1925 – Roman Catholic papal encyclical Quas primas introduces the Feast of Christ the King.
1927 – Guangzhou Uprising: Communist Red Guards launch an uprising in Guangzhou, China, taking over most of the city and announcing the formation of a Guangzhou Soviet.