Here is a list of things which happened on the 20th of August over the years:
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. (636)
Lewis and Clark Expedition: the “Corps of Discovery”, exploring the Louisiana Purchase, suffers its only death when sergeant Charles Floyd dies, apparently from acute appendicitis. (1804)
Charles Darwin first publishes his theory of evolution in The Journal of the Proceedings of the Linnean Society of London, alongside Alfred Russel Wallace’s same theory. (1858)
President Andrew Johnson formally declares the American Civil War over. (1866)
World War I: German forces occupy Brussels. (1914)
The Soviet Union publicly acknowledges that it had tested a hydrogen bomb. (1953)
President Lyndon B. Johnson signed a nearly $1 billion anti-poverty measure. (1964)
Viking Program: NASA launches the Viking 1 planetary probe toward Mars. (1975)
The United States launched Voyager 2, an unmanned spacecraft carrying a 12-inch copper phonograph record containing greetings in dozens of languages, samples of music and sounds of nature. (1977)
Lebanese Civil War: a multinational force lands in Beirut to oversee the PLO’s withdrawal from Lebanon. (1982)
“Black Saturday” of the Yellowstone fire in Yellowstone National Park (1988)
Collapse 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. (1991)
Estonia secedes from the Soviet Union. (1991)
After rounds of secret negotiations in Norway, the Oslo Peace Accords are signed, followed by a public ceremony in Washington, D.C. the following month. (1993)
The Supreme Court of Canada rules that Quebec cannot legally secede from Canada without the federal government’s approval. (1998)
U.S. embassy bombings: the United States military launches cruise missile attacks against alleged al-Qaida 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)
A group of Iraqis opposed to the regime of Saddam Hussein take over the Iraqi Embassy in Berlin for five hours before releasing their hostages and surrendering. (2002)
Spanair Flight 5022, from Madrid to Gran Canaria, skids off the runway and crashes at Barajas Airport. 146 people are killed in the crash, 8 more die afterwards. Only 18 people survive. (2008)
Secretary of State Condoleezza Rice and Polish Foreign Minister Radek Sikorski signed a deal to put a U.S. missile defense base in Poland. (2008)