Wikipedia:Selected anniversaries/August 20
August 20: St. Stephen's Day in Hungary.
- 917 – Byzantine-Bulgarian Wars: Bulgarians led by Tsar Simeon I (seal pictured) drove the Byzantines out of Thrace with a decisive victory in the Battle of Anchialus.
- 1794 – American troops defeated the Western Confederacy, an alliance of various Native American tribes, at the Battle of Fallen Timbers, the decisive battle of the Northwest Indian War.
- 1804 – The Lewis and Clark Expedition, exploring the Louisiana Purchase, suffered its only death when Sergeant Charles Floyd died, apparently from acute appendicitis.
- 1968 – At least 200,000 Warsaw Pact troops and 5,000 tanks began to invade Czechoslovakia, abruptly ending a period of political liberalization known as "Prague Spring" with the result of 72 dead Czechoslovaks and the arrest and extradition of their leader Alexander Dubček to the Soviet Union.
- 1991 – Estonia regained its independence in the Singing Revolution, breaking away from the Soviet Union.
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