August 12

• August 12, 30 BC
  Cleopatra, the most famous queen and the last active pharaoh of Ancient Egypt, kills herself by inducing an Egyptian cobra to bite her after her beloved Mark Antony's suicide
• August 12, 1093
  In England the foundation stone for Durham Cathedral is laid down
• August 12, 1332
  Rebels supporting the Balliol beat forces of the infant David II, the son of Robert the Bruce at the Battle of Dupplin Moor in Scotland
• August 12, 1399
  Battle of the Vorskla River, a major battle between joint armies of Tokhtamysh and Grand Duke Vytautas of Lithuania, and the Tatars, under Edigu and Temur Qutlugh, ends in a decisive Tatar victory
• August 12, 1508
  Juan Ponce de León, a Spanish explorer, arrives to New World to conquer the Puerto Rico
• August 12, 1648
  Seven-year-old Mehmed IV succeeds Ibrahim in the Ottoman House of Osman
• August 12, 1687
  At the Battle of Mohács, Hungary, the forces of Holy Roman Emperor Leopold I, commanded by Charles of Lorraine defeated the Turks
• August 12, 1759
  Forces of Frederick the Great are defeated by combined army of Russians and Austrians under Pyotr Saltykov at Kunersdorf, which gives the victors the opportunity to march against Berlin
• August 12, 1812
  British commander the Duke of Wellington occupies Madrid, Spain, forcing out Joseph Bonaparte
• August 12, 1851
  Isaac Singer, the founder of the Singer Sewing Machine Company, is granted a patent for his sewing machine
• August 12, 1883
  The last quagga, subspecies of the plains zebra, dies at the Artis Magistra zoo in Amsterdam
• August 12, 1896
  Gold is discovered at Dawson on the Klondike River in Alaska, triggering Klondike Gold Rush in Canada
• August 12, 1981
  At the Waldorf-Astoria Hotel in New York City, and in Boca Raton, Florida, IBM announces the model 5150, called IBM Personal Computer, a progenitor of the IBM PC compatible hardware platform
• August 12, 1982
  Mexico announces it is unable to pay its large foreign debt, triggering a debt crisis that quickly spreads throughout Latin America
• August 12, 1985
  Japan Airlines Flight 123 crashes in Japan, killing 520 people becoming the worst single-aircraft disaster in history
• August 12, 1990
  The largest and most complete skeleton of a Tyrannosaurus rex, called "Sue", is discovered near Faith, South Dakota
• August 12, 2000
  The Russian submarine K-141 Kursk sinks in the Barents Sea, resulting in the deaths of all 118 men on board

March 13

• March 13, 624
  Muslims under Muhammad defeat non-believers for the first time at the Battle of Badr
• March 13, 1401
  Samogitian uprisings supported by Vytautas took place against the German knights in Great Duchy of Lithuania
• March 13, 1560
  Ottoman navy defeats the Spanish fleet at the Battle of Djerba
• March 13, 1567
  A Spanish professional army under General Beauvoir defeat an army of Dutch radical Calvinists rebels under Jan de Marnix at the Battle of Oosterweel during Dutch Revolt
• March 13, 1569
  Henry of Anjou, count of Anjou, defeat the Huguenots at the Battle of Jarnac during which co-leader of Huguenots Louis Conde dies
• March 13, 1591
  Moroccan forces of the Sultan Ahmad al-Mansur led by Judar Pasha defeat Askia Ishaq II at the Battle of Tondibi ending the Songhai Empire
• March 13, 1610
  Galileo publishes his observations of the night sky under the title Sidereus Nuncius
• March 13, 1634
  King Louis XIII at the urging of Cardinal Richelieu granted letters patent to formally establish the Académie française in Paris, responsible for the regulation of French grammar, orthography, and literature
• March 13, 1781
  British astronomer William Herschel discovers the planet Uranus, assuming it is a comet and names it Georgium Sidus, in honor of George III
• March 13, 1852
  A familiar symbol of the United States, Uncle Sam, makes his debut as a cartoon character in the New York Lantern
• March 13, 1855
  Percival Lowell, an American businessman and astronomer, is born
• March 13, 1881
  Alexander II, Emperor of Russia, and one of the most successful Russian reformers, is assassinated at age 62 when a bomb is thrown at him near his palace by the anarchist group
• March 13, 1883
  Sergey Degayev, a Russian terrorist, shots and kills Russian Gendarme colonel Georgy Sudeykin, security chief of Emperor Alexander III
• March 13, 1884
  Muhammad Ahmad, proclaimed himself the prophesied redeemer of Islam, begins successful siege of British-led Egyptian garrison at Khartoum during the Mahdist War in Sudan
• March 13, 1920
  Wolfgang Kapp's coup attempt in Berlin, Germany, fails
• March 13, 1923
  Lee de Forest demonstrates his sound-on-film moving pictures to the press in New York City, New York
• March 13, 1928
  450 die in Saint Francis Valley Dam burst in California
• March 13, 1933
  Joseph Goebbels becomes German minister of Information and Propaganda
• March 13, 1940
  Finland and the Soviet Union end Winter War concluding the Moscow Peace Treaty by which Finland retains independence but gives up the Karelian Isthmus, Viipuri, and a small band of land north of Lake Ladoga to the Soviet Union
• March 13, 1943
  In Smolensk, a bomb disguised as two bottles of brandy is put on board Adolf Hitler's personal Focke-Wulf 200 Condor plane; the detonator activates, but due to cold temperature, the plastic explosives do not detonate
• March 13, 1989
  Six million people in the northeastern U.S. and in Sweden are left without power for nine hours after a geomagnetic storm causes the collapse of the Hydro-Quebec power grid
• March 13, 1997
  India's Missionaries of Charity chooses Sister Nirmala to succeed Mother Teresa as its leader