On July 25:
285 Diocletian appointed Maximian as Caesar, co-ruler.
306 Constantine I was proclaimed Roman emperor by his troops.
864 The Edict of Pistres of Charles the Bald ordered defensive measures against the Vikings.
1139 Battle of Ourique: The independence of Portugal from the Kingdom of León declared after the Almoravids, led by Ali ibn Yusuf, were defeated by Prince Afonso Henriques.
1261 The city of Constantinople was recaptured by Nicaean forces under the command of Alexios Strategopoulos, re-establishing the Byzantine Empire.
1536 Sebastián de Belalcázar on his search for El Dorado founded the city of Santiago de Cali.
1547 Henry II of France was crowned.
1567 Don Diego de Losada founds the city of Santiago de Leon de Caracas, modern-day Caracas, the capital city of Venezuela.
1593 Henry IV of France publicly converted from Protestantism to Roman Catholicism.
1603 James VI of Scotland was crowned bringing the Kingdoms of England and Scotland into personal union.
1722 The Three Years War began along the Maine and Massachusetts border.
1755 British governor Charles Lawrence and the Nova Scotia Council ordered the deportation of the Acadians.
1758 Seven Years’ War: the island battery at Fortress Louisbourg in Nova Scotia was silenced and all French warships destroyed or taken.
1788 Wolfgang Mozart completed his Symphony number 40 in g minor (K550).
1792 The Brunswick Manifesto was issued to the population of Paris promising vengeance if the French Royal Famiy was harmed.
1795 The first stone of the Pontcysyllte Aqueduct was laid.
1797 Horatio Nelson lost more than 300 men and his right arm during the failed conquest attempt of Tenerife.
1799 David Douglas, Scottish botanist, was born (d. 1834).
1799 At Aboukir in Egypt, Napoleon I of France defeats 10,000 Ottomans under Mustafa Pasha.
1814 War of 1812: Battle of Lundy’s Lane.
1837 The first commercial use of an electric telegraph was successfully demonstrated by William Cooke and Charles Wheatstone on 25 July 1837 between Euston and Camden Town.
1853 Joaquin Murietta, the Californio bandit known as “Robin Hood of El Dorado”, was killed.
1861 American Civil War: the Crittenden-Johnson Resolution was passed by the U.S. Congress stating that the war was being fought to preserve the Union and not to end slavery.
1866 The U.S. Congress passed legislation authorizing the rank of General of the Army (commonly called “5-star general”). Lieutenant General Ulysses S. Grant becomes the first to be promoted to this rank.
1869 The Japanese daimyō began returning their land holdings to the emperor as part of the Meiji Restoration reforms.
1894 The First Sino-Japanese War began when the Japanese fired on a Chinese warship.
1898 The United States invasion of Puerto Rico began with U.S. troops led by General Nelson Miles landing at harbour of Guánica.
1907 Korea became a protectorate of Japan.
1908 Ajinomoto was founded. Kikunae Ikeda of the Tokyo Imperial University discovered that a key ingredient in Konbu soup stock was monosodium glutamate (MSG), and patented a process for manufacturing it.
1909 Louis Blériot made the first flight across the English Channel in a heavier-than-air machine, from Calais to Dover in 37 minutes.
1915 RFC Captain Lanoe Hawker became the first British military aviator to earn the Victoria Cross, for defeating three German two-seat observation aircraft in one day, over the Western Front.
1917 Sir Thomas Whyte introduced the first income tax in Canada as a “temporary” measure (lowest bracket 4% and highest 25%).
1920 Telecommunications: the first transatlantic two-way radio broadcast.
1925 Telegraph Agency of the Soviet Union (TASS) was established.
1930 Murray Chapple, New Zealand cricketer, was born (d. 1985).
1934 Nazis assassinated Austrian Chancellor Engelbert Dollfuss in a failed coup attempt.
1940 General Guisan ordered the Swiss Army to resist German invasion and makes surrender illegal.
1942 Bruce Woodley, Australian musician (The Seekers), was born.
1942 Norwegian Manifesto called for nonviolent resistance to the Nazis
1943 Jim McCarty, English musician (The Yardbirds), was born.
1943 Benito Mussolini was forced out of office by his own Italian Grand Council and replaced by Pietro Badoglio.
1944 Operation Spring – one of the bloodiest days for the First Canadian Army during WWII: 1,500 casualties, including 500 killed.
1946 Operation Crossroads: an atomic bomb was detonated underwater in the lagoon of Bikini atoll.
1946 Dean Martin and Jerry Lewis staged their first show as a comedy team.
1948 The Australian cricket team set a world record for the highest successful run-chase in Test cricket history in the Fourth Test against England.
Donald Bradman, the Australian captain.
1951 Verdine White, American musician (Earth, Wind & Fire), was born.
1953 Robert Zoellick, President of the World Bank, was born.
1956 Italian ocean liner SS Andrea Doria collided with the MS Stockholm in heavy fog and sank the next day, killing 51.
1957 Republic of Tunisia proclaimed.
1958 The African Regroupment Party (PRA) held its first congress in Cotonou.
1959 SR-N1 hovercraft crossed the English Channel from Calais to Dover in just over 2 hours.
1965 Bob Dylan went electric as he plug in at the Newport Folk Festival, signaling a major change in folk and rock music.
1969 Vietnam War: US President Richard Nixon declared the Nixon Doctrine, stating that the United States expected its Asian allies to take care of their own military defense.
1973 Soviet Mars 5 space probe launched.
1978 The Cerro Maravilla incident – two young Puerto Rican pro-independence activists were killed in a police ambush.
1978 Louise Brown, the world’s first “test tube baby” was born.
1981 The invasion of Hamilton’s Rugby Park by 350 anti-tour demonstrators forced the Springboks-Waikato match to be abandoned.
1983 Black July: 37 Tamil political prisoners at the Welikada high security prison in Colombo were massacred by the fellow Sinhalese prisoners.
Sinhalese mob burns Tamil shops.
1984 Salyut 7 Cosmonaut Svetlana Savitskaya became the first woman to perform a space walk.
1993 Israel launched a massive attack against terrorist forces in Lebanon.
1993 The St James Church massacre in Kenilworth, Cape Town, South Africa.
1994 Israel and Jordan signed the Washington Declaration, which formally ends the state of war that had existed between the nations since 1948.
1995 A gas bottle exploded in Saint Michel station in Paris. Eight were killed and 80 wounded.
1996 In a military coup in Burundi, Pierre Buyoya deposed Sylvestre Ntibantunganya.
1997 K.R. Narayanan was sworn-in as India’s 10th president and the first Dalit— formerly called “untouchable”— to hold this office.
2000 Air France Flight 4590, a Concorde supersonic passenger jet, F-BTSC, crashed just after takeoff from Paris killing all 109 aboard and 4 on the ground.
2007 Pratibha Patil was sworn in as India’s first woman president.
Sourced from NZ History Online & Wikipedia