August 21

 August 21 is the 233rd day of the year (234th in leap years) in the Gregorian calendar. There are 132 days remaining until the end of the year.

Events

• 1139 – Song Dynasty general Yue Fei defeats an army led by Jin Dynasty general Wanyan Wuzhu at the Battle of Yancheng during the Jin–Song wars.
• 1192 – Minamoto no Yoritomo becomes Seii Tai Shōgun and the de facto ruler of Japan. (Traditional Japanese date: July 12, 1192)
• 1331 – King Stephen Uroš III, after months of anarchy, surrenders to his son and rival Stephen Dušan, who succeeds as King of Serbia.
• 1680 – Pueblo Indians capture Santa Fe from Spanish during the Pueblo Revolt.
• 1689 – The Battle of Dunkeld in Scotland.
• 1770 – James Cook formally claims eastern Australia for Great Britain, naming it New South Wales.
• 1772 – King Gustav III completes his coup d'état by adopting a new Constitution, ending half a century of parliamentary rule in Sweden and installing himself as an enlightened despot.
• 1778 – American Revolutionary War: British forces begin besieging the French outpost at Pondichéry.
• 1808 – Battle of Vimeiro: British and Portuguese forces led by General Arthur Wellesley defeat French force under Major-General Jean-Andoche Junot near the village of Vimeiro, Portugal, the first Anglo-Portuguese victory of the Peninsular War.
• 1810 – Jean-Baptiste Bernadotte, Marshal of France, is elected Crown Prince of Sweden by the Swedish Riksdag of the Estates.
• 1821 – Jarvis Island is discovered by the crew of the ship, Eliza Frances.
• 1831 – Nat Turner leads black slaves and free blacks in a rebellion.
• 1852 – Tlingit Indians destroy Fort Selkirk, Yukon Territory.
• 1863 – Lawrence, Kansas is destroyed by Confederate guerrillas Quantrill's Raiders in the Lawrence Massacre.
• 1879 – The Virgin Mary, along with St. Joseph and St. John the Evangelist, reportedly appears at Knock Shrine in Knock, County Mayo, Ireland.
• 1883 – An F5 tornado strikes Rochester, Minnesota, leading to the creation of the Mayo Clinic.
• 1888 – The first successful adding machine in the United States is patented by William Seward Burroughs.
• 1897 – Oldsmobile, a brand of American automobiles was founded.
• 1911 – The Mona Lisa is stolen by a Louvre employee.
• 1914 – World War I: The Battle of Charleroi, a successful German attack across the River Sambre which pre-empted a French offensive in the same area.
• 1918 – World War I: The Second Battle of the Somme begins.
• 1942 – World War II: The flag of Nazi Germany is installed atop the Mount Elbrus, the highest peak of the Caucasus mountain range.
• 1942 – World War II: The Guadalcanal Campaign: American forces defeat an attack by Imperial Japanese Army soldiers in the Battle of the Tenaru.
• 1944 – Dumbarton Oaks Conference, prelude to the United Nations, begins.
• 1944 – World War II: Canadian and Polish units capture the strategically important town of Falaise, Calvados, France.
• 1945 – Physicist Harry K. Daghlian, Jr. is fatally irradiated in a criticality accident during an experiment with the Demon core at Los Alamos National Laboratory.
• 1957 – The Soviet Union successfully conducts a long-range test flight of the R-7 Semyorka, the first intercontinental ballistic missile.
• 1959 – United States President Dwight D. Eisenhower signs an executive order proclaiming Hawaii the 50th state of the union. Hawaii's admission is currently commemorated by Hawaii Admission Day
• 1961 – Motown releases what would be its first #1 hit, "Please Mr. Postman" by The Marvelettes.
• 1963 – Xá Lợi Pagoda raids: The Army of the Republic of Vietnam Special Forces loyal to Ngo Dinh Nhu, brother of President Ngo Dinh Diem, vandalizes Buddhist pagodas across the country, arresting thousands and leaving an estimated hundreds dead.
• 1968 – Nicolae Ceaușescu, leader of Communist Romania, publicly condemns the Soviet led Warsaw Pact invasion of Czechoslovakia, encouraging the Romanian population to arm itself against possible Soviet reprisals.
• 1968 – James Anderson, Jr. posthumously receives the first Medal of Honor to be awarded to an African American U.S. Marine.
• 1969 – An Australian, Denis Michael Rohan, sets the Al-Aqsa Mosque on fire, a major catalyst of the formation of the Organisation of Islamic Cooperation.
• 1971 – A bomb exploded in the Liberal Party campaign rally in Plaza Miranda, Manila, Philippines with several anti-Marcos political candidates injured.
• 1976 – Operation Paul Bunyan at Panmunjom, South Korea.
• 1979 – Soviet dancer Alexander Godunov defects to the United States.
• 1982 – Lebanese Civil War: The first troops of a multinational force lands in Beirut to oversee the Palestine Liberation Organization's withdrawal from Lebanon.
• 1983 – Philippine opposition leader Benigno Aquino, Jr. is assassinated at the Manila International Airport (now renamed Ninoy Aquino International Airport).
• 1986 – Carbon dioxide gas erupts from volcanic Lake Nyos in Cameroon, killing up to 1,800 people within a 20-kilometer range.
• 1991 – Latvia declares renewal of its full independence after the occupation of Soviet Union.
• 1991 – Coup attempt against Mikhail Gorbachev collapses.
• 1992 – Ruby Ridge Standoff in Idaho
• 1993 – NASA loses contact with the Mars Observer spacecraft.
• 2001 – NATO decides to send a peace-keeping force to the former Yugoslav Republic of Macedonia.
• 2001 – The Red Cross announces that a famine is striking Tajikistan, and calls for international financial aid for Tajikistan and Uzbekistan.
• 2013 – Hundreds of people are reported killed by chemical attacks in the Ghouta region of Syria.