- 1240: Mongol invasion of Rus’: Kiev under Daniel of Galicia and Voivode Dmytro falls to the Mongols under Batu Khan.
- 1648: Colonel Thomas Pride of the New Model Army purges the Long Parliament of MPs sympathetic to King Charles I of England, in order for the King’s trial to go ahead; came to be known as “Pride’s Purge”.
- 1704: Battle of Chamkaur: During the Mughal-Sikh Wars, an outnumbered Sikh Khalsa defeats a Mughal army.
- 1745: Charles Edward Stuart’s army begins retreat during the second Jacobite Rising.
- 1846: American and Californio forces clash at the Battle of San Pasqual.
- 1904: Theodore Roosevelt articulated his “Corollary” to the Monroe Doctrine, stating that the U.S. would intervene in the Western Hemisphere should Latin American governments prove incapable or unstable.
- 1916: World War I: The Central Powers capture Bucharest.
- 1917: Finland declares independence from Soviet Russia.
- 1917: Halifax Explosion: A munitions explosion near Halifax, Nova Scotia kills more than 1,900 people in the largest artificial explosion up to that time.
- 1917: World War I: USS Jacob Jones is the first American destroyer to be sunk by enemy action when it is torpedoed by German submarine SM U-53.
- 1921: The Anglo-Irish Treaty is signed in London by British and Irish representatives.
- 1928: The government of Colombia sends military forces to suppress a month-long strike by United Fruit Company workers, resulting in an unknown number of deaths.
- 1941: World War II: The United Kingdom and Canada declare war on Finland in support of the Soviet Union during the Continuation War. Camp X opens in Canada to begin training Allied Secret Agents for the War.
- 1942: World War II in villages Stary Ciepielów and Rekówka German Genarmerie massacred 31 Poles for helping the Jews. Also, two Jewish refugees were murdered.
- 1971: Pakistan severs diplomatic relations with India, initiating the Indo-Pakistani War of 1971.
- 1982: The Troubles: The Irish National Liberation Army bombs a pub frequented by British soldiers in Ballykelly, Northern Ireland, killing eleven soldiers and six civilians.
- 1991: Yugoslav Wars: In Croatia, forces of the Serb-dominated Yugoslav People’s Army (JNA) bombard Dubrovnik after laying siege to the city for seven months.
- 2005: An Iranian Air Force C-130 military transport aircraft crashes into a ten-floor apartment building in a residential area of Tehran, killing all 94 on board and 12 more on the ground.
- For the entire Armed Forces of Ukraine, Armed Forces Day (Ukrainian: День Збройних сил України) is celebrated on 6 December, with fireworks displays and gun salutes nationwide. This holiday was established in 1993 by a resolution passed by the Verkhovna Rada.
- 1608: George Monck, 1st Duke of Albemarle, English general and politician, Lord Lieutenant of Ireland (d. 1670).
- 1833: John S. Mosby, American colonel (d. 1916).
- 1849: August von Mackensen, German field marshal (d. 1945).
- 1886: Joyce Kilmer, American soldier, author, and poet (d. 1918).
- 1892: Osbert Sitwell, English-Italian captain, poet, and author (d. 1969).
- 1893: Homer N. Wallin, American admiral (d. 1984).
- 1916: Yekaterina Budanova, Russian captain and pilot (d. 1943).
- 1917: Dean Hess, American minister and colonel (d. 2015).
- 1922: Benjamin A. Gilman, American soldier and politician (d. 2016).
- 1933: Donald J. Kutyna, American general.
- 762: Muhammad al-Nafs al-Zakiyya, Arab rebel leader (b. 710).
- 1889: Jefferson Davis, American general and politician, President of the Confederate States of America (b. 1808).
- 1974: Nikolay Kuznetsov, Soviet naval officer (b. 1904).
- 2005: William P. Yarborough, American general (b. 1912).
- 2015: Liu Juying, Chinese general and politician (b. 1917).