August 21

• August 21, 1680
  Pueblo Indians take possession of Santa Fe and drives the Spanish out of New Mexico until 1692 during the Pueblo Revolt
• August 21, 1770
  British navigator, James Cook formally claims the East Coast of Australia for Great Britain, naming it New South Wales during his first voyage
• August 21, 1808
  Napoleon Bonaparte's General Jean-Andoche Junot is defeated by British General Arthur Wellesley at the first Battle of the Peninsular War at Vimeiro, Portugal
• August 21, 1810
  Sweden's Riksdag elects Jean-Baptiste Bernadotte, Marshal of France under Napoleon, as heir apparent to the Swedish throne
• August 21, 1841
  John Hampson of New Orleans patents the Window blind
• August 21, 1944
  Dumbarton Oaks conference, which establishes United Nations, opens in Washington, DC
• August 21, 1968
  Radio Prague, Czechoslovakia, at 12:50 AM announces a Soviet-led invasion, after Warsaw Pact forces enter Czechoslovakia to end reform movement known as Prague Spring
• August 21, 1986
  A limnic eruption at Lake Nyos in Cameroon triggers the sudden release of about 200,000 tons of carbon dioxide and causes death of 1,744 people
• August 21, 2013
  1,429 are killed in the Ghouta chemical attack during the Syrian Civil War, blamed on President Bashar al-Assad