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

April 22

• April 22, 1073
  Gregory VII, Hildebrand of Sovana, becomes Pope after death of Pope Alexander II
• April 22, 1370
  The first stone of the Bastille is laid by order of King Charles V in order to defend Paris from England forces during Hundred Year War
• April 22, 1453
  The Ottomans haul 76 warships out of the water and drag them on wood rails to bypass the Greek blockade of the Constantinople harbor
• April 22, 1509
  Henry VIII ascends to English throne after death of his father Henry VII to become the second monarch of the Tudor dynasty
• April 22, 1529
  Treaty of Zaragoza defines the antimeridian of Tordesillas attributing the Moluccas to Portugal and Philippines to Spain
• April 22, 1676
  Netherlands and Spain forces are defeated by France in the Battle of Augusta, a Dutch skilled admiral Michiel de Ruyter is fatally wounded
• April 22, 1724
  Immanuel Kant, a German philosopher, is born in Konigsberg, modern-day Kaliningrad
• April 22, 1745
  Treaty of Fussen is signed between the Electorate of Bavaria and Habsburg Austria, restoring the status quo of Germany
• April 22, 1826
  Ibrahim Pasha, son of Muhammad Ali of Egypt, takes Missolonghi in West Greece after a long siege
• April 22, 1876
  Pyotr Ilyich Tchaikovsky, a Russian composer, completes his "Swan Lake" ballet
• April 22, 1898
  The United States Navy begin blockading Cuban ports under orders from President McKinley, formally declaring war between the United States and Spain
• April 22, 1915
  Second Battle of Ypres, marked by the first mass use of poison gas, begins between German Empire and Allies
• April 22, 1930
  United States, Britain and Japan sign London Naval Treaty to reduce naval forces, which is strongly opposed by the Japanese military and inflames growing anti-foreign sentiment and militarism
• April 22, 1943
  British Royal Air Force shoots down 14 German transport planes over Mediterranean Sea
• April 22, 1970
  First Earth Day held internationally to conserve natural resources
• April 22, 1977
  Simon Peres, a Polish-born Israeli statesman, becomes premier of Israel
• April 22, 1978
  The One Love Peace Concert is held at National Heroes Stadium in Kingston, Jamaica, where Bob Marley unites two opposing political leaders at this concert, bringing peace to the civil war-ridden streets of the city
• April 22, 2010
  The Deepwater Horizon oil rig off the Louisiana coast sinks into the Gulf of Mexico two days after an explosion tore through it, leaving the largest oil spill in United States history with 492,000 tonnes of oil