25 August

357 – Battle of Strasbourg: Julian, Caesar (deputy emperor) and supreme commander of the Roman army in Gaul, wins an important victory against the Alemanni at Strasbourg (Argentoratum).
450 – Pulcheria becomes empress of the Byzantine Empire after her brother Theodosius II is killed during an hunting accident. She marries the Illyrian (or Thracian) senator Marcian who is crowned as emperor.
1248 – The Dutch city of Ommen receives city rights and fortification rights from Otto III, the Archbishop of Utrecht.
1258 – Regent George Mouzalon and his brothers are killed during a coup headed by the aristocratic faction under, paving the way for its leader, Michael VIII Palaiologos, to ultimately usurp the throne of the Empire of Nicaea.
1537 – The Honourable Artillery Company, the oldest surviving regiment in the British Army, and the second most senior, is formed.
1580 – Battle of Alcântara. Spain defeats Portugal.
1609 – Galileo Galilei demonstrates his first telescope to Venetian lawmakers.
1758 – Seven Years' War: Frederick II of Prussia defeats the Russian army at the Battle of Zorndorf.
1768 – James Cook begins his first voyage.
1825 – Uruguay declares its independence from Brazil.
1830 – The Belgian Revolution begins.
1835 – The New York Sun perpetrates the Great Moon Hoax.
1875 – Captain Matthew Webb became the first person to swim across the English Channel, traveling from Dover, England, to Calais, France, in 22 hours.
1894 – Kitasato Shibasaburō discovers the infectious agent of the bubonic plague and publishes his findings in The Lancet.
1898 – 700 Greek civilians, 17 British guards and the British Consul of Crete are killed by a Turkish mob in Heraklion, Greece.
1912 – The Kuomintang, the Chinese nationalist party, is founded.
1914 – World War I: The library of the Catholic University of Leuven is deliberately destroyed by the German Army. Hundreds of thousands of irreplaceable volumes and Gothic and Renaissance manuscripts are lost.
1916 – The United States National Park Service is created.
1920 – Polish-Soviet War: Battle of Warsaw, which began on August 13, ends. The Red Army is defeated.
1921 – The first skirmishes of the Battle of Blair Mountain occur.
1933 – The Diexi earthquake strikes Mao County, Sichuan, China and kills 9,000 people.
1939 – The United Kingdom and Poland form a military alliance in which the UK promises to defend Poland in case of invasion by a foreign power.
1942 – World War II: Battle of Milne Bay, Papua New Guinea.
1942 – World War II: second day of the Battle of the Eastern Solomons. A Japanese naval transport convoy headed towards Guadalcanal is turned-back by an Allied air attack, losing one destroyer and one transport sunk, and one light cruiser heavily damaged.
1944 – World War II: Paris is liberated by the Allies.
1945 – Ten days after World War II ends with Japan announcing its surrender, armed supporters of the Communist Party of China kill Baptist missionary John Birch, regarded by some of the American right as the first victim of the Cold War.
1948 – The House Un-American Activities Committee holds first-ever televised congressional hearing: "Confrontation Day" between Whittaker Chambers and Alger Hiss.
1950 – President Harry Truman orders the US Army to seize control of the nation's railroads to avert a strike.
1961 – President Jânio Quadros of Brazil resigns after just seven months in power.
1980 – Zimbabwe joins the United Nations.
1981 – Voyager 2 spacecraft makes its closest approach to Saturn
1989 – Tadeusz Mazowiecki is chosen as the first non-communist Prime Minister in Central and Eastern Europe.
1989 – Voyager 2 spacecraft makes its closest approach to Neptune, the outermost planet in the Solar System.
1989 – Mayumi Moriyama becomes Japan's first female cabinet secretary.
1991 – The Airbus A340 aircraft makes it's first flight.
1991 – Belarus gains its independence from the Soviet Union
1991 – The Battle of Vukovar begins. An 87-day siege of a Croatian city by the Yugoslav People's Army (JNA), supported by various Serbian paramilitary forces, between August–November 1991 during the Croatian War of Independence
1991 – Linus Torvalds announces the first version of what will become Linux.
1997 – Egon Krenz, the former East German leader, is convicted of a shoot-to-kill policy at the Berlin Wall.
2003 – The Tli Cho land claims agreement is signed between the Dogrib First Nations and the Canadian federal government in Rae-Edzo (now called Behchoko).

Holidays and observances

Christian Feast Day:
Æbbe of Coldingham
Aredius
Genesius of Arles
Gregory of Utrecht
Joseph Calasanctius
Louis IX of France
Menas of Constantinople
Patricia of Naples
Earliest date on which La Tomatina can fall, while August 31 is the latest; celebrated on the last Wednesday in August. (Buñol)
Independence Day, celebrates the independence of Uruguay from Brazil in 1825.
Liberation Day (Paris)
Opiconsivia held in honor of Ops. (Roman Empire)
Soldier's Day (Brazil)