August 12 is the 224th day of the year (225th in leap years) in the Gregorian calendar. 141 days remain until the end of the year.
It is the peak of the Perseid meteor shower. It is also known as the "Glorious Twelfth" in the United Kingdom, as it marks the traditional start of the grouse shooting season.
- 1099 – First Crusade: Battle of Ascalon Crusaders under the command of Godfrey of Bouillon defeat Fatimid forces led by Al-Afdal Shahanshah. This is considered the last engagement of the First Crusade.
- 1121 – Battle of Didgori: The Georgian army under King David IV wins a decisive victory over the famous Seljuk commander Ilghazi.
- 1164 – Battle of Harim: Nur ad-Din Zangi defeats the Crusader armies of the County of Tripoli and the Principality of Antioch.
- 1323 – Signature of the Treaty of Nöteborg between Sweden and Novgorod Republic, which regulates the border between the two countries for the first time.
- 1492 – Christopher Columbus arrives in the Canary Islands on his first voyage to the New World.
- 1499 – First engagement of the Battle of Zonchio between Venetian and Ottoman fleets.
- 1624 – The president of Louis XIII of France's royal council is arrested, leaving Cardinal Richelieu in the role of the King's principal minister.
- 1676 – Praying Indian John Alderman shoots and kills Metacomet, the Wampanoag war chief, ending King Philip's War.
- 1687 – Battle of Mohács: Charles of Lorraine defeats the Ottoman Empire.
- 1765 – Treaty of Allahabad is signed. The Treaty marks the political and constitutional involvement and the beginning of Company rule in India.
- 1793 – The Rhône and Loire départments are created when the former département of Rhône-et-Loire is split into two.
- 1806 – Santiago de Liniers, 1st Count of Buenos Aires re-takes the city of Buenos Aires, Argentina after the first British invasion.
- 1831 – French intervention forces William I of the Netherlands to abandon his attempt to suppress the Belgian Revolution.
- 1851 – Isaac Singer is granted a patent for his sewing machine.
- 1865 – Joseph Lister, British surgeon and scientist, performs 1st antiseptic surgery.
- 1883 – The last quagga dies at the Natura Artis Magistra, a zoo in Amsterdam, Netherlands.
- 1898 – The Hawaiian flag is lowered from ʻIolani Palace in an elaborate annexation ceremony and replaced with the flag of the United States to signify the transfer of sovereignty from the Republic of Hawaii to the United States.
- 1914 – World War I: The United Kingdom declares war on Austria-Hungary; the countries of the British Empire follow suit.
- 1914 – World War I: The Battle of Halen a.k.a. Battle of the Silver Helmets a clash between large Belgian and German cavalry formations at Halen, Belgium.
- 1944 – Waffen-SS troops massacre 560 people in Sant'Anna di Stazzema.
- 1944 – Nazi German troops end the week-long Wola massacre, during which time at least 40,000 people are killed indiscriminately or in mass executions.
- 1944 – Alençon is liberated by General Philippe Leclerc de Hauteclocque, the first city in France to be liberated from the Nazis by French forces.
- 1948 – Babrra massacre: About 600 unarmed members of the Khudai Khidmatgar movement are shot dead on the orders of the Chief Minister of the North-West Frontier Province, Abdul Qayyum Khan Kashmiri, on Babrra ground in the Hashtnagar region of Charsadda District, North-West Frontier Province (now Khyber Pakhtunkhwa), Pakistan.
- 1950 – Korean War: Bloody Gulch massacre: 75 American POWs are massacred by North Korean Army.
- 1952 – The Night of the Murdered Poets: Thirteen prominent Jewish intellectuals are murdered in Moscow, Russia, Soviet Union.
- 1953 – The first testing of a real thermonuclear weapon (not test devices): The Soviet atomic bomb project continues with the detonation of "RDS-6s" (Joe 4), the first Soviet thermonuclear bomb.
- 1953 – The 7.2 Ms Ionian earthquake shakes the southern Ionian Islands with a maximum Mercalli intensity of X (Extreme). Between 445 and 800 people are killed.
- 1960 – Echo 1A, NASA's first successful communications satellite, is launched.
- 1964 – South Africa is banned from the Olympic Games due to the country's racist policies.
- 1969 – Violence erupts after the Apprentice Boys of Derry march in Derry, Northern Ireland, resulting in a three-day communal riot known as the Battle of the Bogside.
- 1976 – Between 1,000 and 3,500 Palestinians are killed in the Tel al-Zaatar massacre, one of the bloodiest events of the Lebanese Civil War.
- 1977 – The first free flight of the Space Shuttle Enterprise.
- 1977 – The Sri Lanka Riots:, targeting the minority Sri Lankan Tamils, begin, less than a month after the United National Party came to power. Over 300 Tamils are killed.
- 1981 – The IBM Personal Computer is released.
- 1985 – Japan Airlines Flight 123 crashes into Osutaka ridge in Gunma Prefecture, Japan, killing 520, to become the worst single-plane air disaster.
- 1990 – Sue, the largest and most complete Tyrannosaurus rex skeleton found to date, is discovered by Sue Hendrickson in South Dakota.
- 1992 – Canada, Mexico and the United States announce completion of negotiations for the North American Free Trade Agreement (NAFTA).
- 1994 – Major League Baseball players go on strike, forcing the cancellation of the 1994 World Series.
- 2000 – The Russian Navy submarine Kursk explodes and sinks in the Barents Sea during a military exercise, killing her entire 118-man crew.
- 2015 – At least two massive explosions kill 173 people and injure nearly 800 more in Tianjin, China.
- 2017 - Heather Heyer is killed and numerous others are wounded when James Alex Fields Jr. rammed his vehicle into a crowd of counter-protesters during a white supremacist Unite the Right rally in Charlottesville, Virginia.
- 2018 – Thirty-nine civilians, including a dozen children, are killed in an explosion at a weapons depot in a rebel-held town in northwest Syria.
srpskohrvatski / српскохрватски: 12. 8.