August 20 events in history

14 Agrippa Postumus, adopted son of the late Roman emperor Augustus, is executed by his guards while in exile under mysterious circumstances
636 Battle of Yarmouk: Arab forces led by Khalid ibn al-Walid take control of Syria and Palestine away from the Byzantine Empire, marking the first great wave of Muslim conquests and the rapid advance of Islam outside Arabia
917 Battle of Acheloos: Tsar Simeon I of Bulgaria decisively defeats a Byzantine army
1000 The foundation of the Hungarian state by Saint Stephen, celebrated as a National Day in Hungary
1083 Canonization of the first King of Hungary, Saint Stephen and his son Saint Emeric
1308 Pope Clement V pardons Jacques de Molay, the last Grand Master of the Knights Templar, absolving him of charges of heresy
1391 Konrad von Wallenrode becomes the 24th Hochmeister of the Teutonic Order
1467 The Second Battle of Olmedo takes places as part of a succession conflict between Henry IV of Castile and his half-brother Alfonso, Prince of Asturias
1519 Philosopher and general Wang Yangming defeats Zhu Chenhao, ending the Prince of Ning rebellion against the reign of the Ming Dynasty emperor Zhengde
1672 Former Grand Pensionary Johan de Witt and his brother Cornelis are brutally murdered by an angry mob in The Hague
1707 The first Siege of Pensacola comes to end with the failure of the British to capture Pensacola, Florida
1710 War of the Spanish Succession: A multinational army led by the Austrian commander Guido Starhemberg defeats the Spanish-Bourbon army commanded by Alexandre Maître, Marquis de Bay in the Battle of Saragossa
1775 The Spanish establish the Presidio San Augustin del Tucson in the town that became Tucson, Arizona
1794 Battle of Fallen Timbers: American troops force a confederacy of Shawnee, Mingo, Delaware, Wyandot, Miami, Ottawa, Chippewa, and Potawatomi warriors into a disorganized retreat
1858 Charles Darwin first publishes his theory of evolution through natural selection in The Journal of the Proceedings of the Linnean Society of London, alongside Alfred Russel Wallace's same theory
1866 President Andrew Johnson formally declares the American Civil War over
1882 Tchaikovsky's 1812 Overture debuts in Moscow, Russia
1910 The Great Fire of 1910 (also commonly referred to as the "Big Blowup" or the "Big Burn") occurs in northeast Washington, northern Idaho (the panhandle), and western Montana, burning approximately 3 million acres (12,000 km2)
1914 World War I: German forces occupy Brussels
1920 The first commercial radio station, 8MK (now WWJ), begins operations in Detroit, Michigan
1926 Japan's public broadcasting company, Nippon Hōsō Kyōkai (NHK) is established
1938 Lou Gehrig hits his 23rd career grand slam, a record that stood for 75 years until it was broken by Alex Rodriguez
1940 In Mexico City, Mexico exiled Russian revolutionary Leon Trotsky is fatally wounded with an ice axe by Ramón Mercader. He dies the next day
1940 World War II: British Prime Minister Winston Churchill makes the fourth of his famous wartime speeches, containing the line "Never was so much owed by so many to so few"
1944 World War II: The Battle of Romania begins with a major Soviet Union offensive
1944 World War II: 168 captured allied airmen, including Phil Lamason, accused by the Gestapo of being "terror fliers", arrive at Buchenwald concentration camp
1950 Korean War: United Nations repel an offensive by North Korean divisions attempting to cross the Naktong River and assault the city of Taegu
1955 In Morocco, a force of Berbers from the Atlas Mountains region of Algeria raid two rural settlements and kill 77 French nationals
1960 Senegal breaks from the Mali Federation, declaring its independence
1962 The NS Savannah, the world's first nuclear-powered civilian ship, embarks on its maiden voyage
1968 Soviet Union-dominated Warsaw Pact troops invade Czechoslovakia, crushing the Prague Spring
1975 Viking Program: NASA launches the Viking 1 planetary probe toward Mars
1977 Voyager Program: NASA launches the Voyager 2 spacecraft
1986 In Edmond, Oklahoma, U.S. Postal employee Patrick Sherrill guns down 14 of his co-workers and then commits suicide
1988 The Troubles: Eight British soldiers are killed and 28 wounded when their bus is hit by an IRA roadside bomb in Ballygawley, County Tyrone
1988 Iran–Iraq War: A ceasefire is agreed after almost eight years of war
1988 Peru becomes a member of the Berne Convention copyright treaty
1988 "Black Saturday" of the Yellowstone fire in Yellowstone National Park
1989 The pleasure boat Marchioness sinks on the River Thames following a collision. Fifty-one people are killed
1989 The O-Bahn Busway in Adelaide, the world's longest guided busway, opens
1991 Estonia, annexed by the Soviet Union in 1940, issues a decision on the re-establishment of independence on the basis of historical continuity of its pre-World War II statehood
1991 Dissolution of the Soviet Union, August Coup: More than 100,000 people rally outside the Soviet Union's parliament building protesting the coup aiming to depose President Mikhail Gorbachev
1993 After rounds of secret negotiations in Norway, the Oslo Accords are signed, followed by a public ceremony in Washington, D.C. the following month
1997 Souhane massacre in Algeria; over 60 people are killed and 15 kidnapped
1998 U.S. embassy bombings: The United States launches cruise missile attacks against alleged al-Qaeda camps in Afghanistan and a suspected chemical plant in Sudan in retaliation for the August 7 bombings of American embassies in Kenya and Tanzania
1998 The Supreme Court of Canada rules that Quebec cannot legally secede from Canada without the federal government's approval
2002 A group of Iraqis opposed to the regime of Saddam Hussein take over the Iraqi Embassy in Berlin, Germany for five hours before releasing their hostages and surrendering
2008 Spanair Flight 5022, from Madrid, Spain to Gran Canaria, skids off the runway and crashes at Barajas Airport. One hundred forty-six people are killed in the crash, and eight more die later. Only 18 people survive
2012 A prison riot in the Venezuelan capital, Caracas, kills at least 20 people
2014 72 people are killed in Japan's Hiroshima prefecture by a series of landslides caused by a month's worth of rain that fell in one day