September 4 is the 247th day of the year (248th in leap years) in the Gregorian calendar; 118 days remain until the end of the year.
476 – Romulus Augustulus is deposed when Odoacer proclaims himself 'King of Italy', thus ending the Western Roman Empire.
626 – Li Shimin, posthumously known as Emperor Taizong of Tang, assumes the throne over the Tang dynasty of China.
929 – Battle of Lenzen: Slavic forces (the Redarii and the Obotrites) are defeated by a Saxon army near the fortified stronghold of Lenzen in Brandenburg.
1282 – Peter III of Aragon becomes the King of Sicily.
1479 – The Treaty of Alcáçovas is signed by the Catholic Monarchs of Castile and Aragon on one side and Afonso V and his son, Prince John of Portugal.
1666 – In London, England, the most destructive damage from the Great Fire occurs.
1774 – New Caledonia is first sighted by Europeans, during the second voyage of Captain James Cook.
1781 – Los Angeles is founded as El Pueblo de Nuestra Señora La Reina de los Ángeles (The Village of Our Lady, the Queen of the Angels) by 44 Spanish settlers.
1800 – The French garrison in Valletta surrenders to British troops who had been called at the invitation of the Maltese. The islands of Malta and Gozo become the Malta Protectorate.
1812 – War of 1812: The Siege of Fort Harrison begins when the fort is set on fire.
1862 – American Civil War Maryland Campaign: General Robert E. Lee takes the Army of Northern Virginia, and the war, into the North.
1870 – Emperor Napoleon III of France is deposed and the Third Republic is declared.
1882 – The Pearl Street Station in New York City becomes the first power plant to supply electricity to paying customers.
1886 – American Indian Wars: After almost 30 years of fighting, Apache leader Geronimo, with his remaining warriors, surrenders to General Nelson Miles in Arizona.
1888 – George Eastman registers the trademark Kodak and receives a patent for his camera that uses roll film.
1923 – Maiden flight of the first U.S. airship, the USS Shenandoah.
1936 – Spanish Civil War: Largo Caballero forms a war cabinet to direct the republican war effort.
1939 – World War II: William J. Murphy commands the first Royal Air Force attack on Germany.
1941 – World War II: A German submarine makes the first attack of the war against a United States warship, the USS Greer.
1944 – World War II: The British 11th Armoured Division liberates the Belgian city of Antwerp.
1944 – World War II: Finland exits from the war with Soviet Union.
1948 – Queen Wilhelmina of the Netherlands abdicates for health reasons.
1950 – Darlington Raceway is the site of the inaugural Southern 500, the first 500-mile NASCAR race.
1951 – The first live transcontinental television broadcast takes place in San Francisco, United States, from the Japanese Peace Treaty Conference.
1957 – American Civil Rights Movement: Little Rock Crisis: The governor of Arkansas calls out the National Guard to prevent African American students from enrolling in Little Rock Central High School, resulting in the lawsuit Cooper v. Aaron the following year.
1964 – Scotland's Forth Road Bridge near Edinburgh officially opens.
1967 – Vietnam War: Operation Swift begins when U.S. Marines engage the North Vietnamese in battle in the Que Son Valley.
1970 – Salvador Allende is elected President of Chile.
1972 – Mark Spitz becomes the first competitor to win seven medals at a single Olympic Games.
1972 – The Price Is Right premieres on CBS. It currently is the longest running game show on American television.
1975 – The Sinai Interim Agreement relating to the Arab–Israeli conflict is signed.
1977 – The Golden Dragon massacre takes place in San Francisco.
1989 – In Leipzig, East Germany, the first of weekly demonstration for the legalisation of opposition groups and democratic reforms takes place.
1998 – Google is founded by Larry Page and Sergey Brin, two students at Stanford University.
2001 – Tokyo DisneySea opens to the public as part of the Tokyo Disney Resort in Urayasu, Chiba, Japan.
2002 – The Oakland Athletics win their 20th consecutive game, an American League record, until the Cleveland Indians surpassed it in 2017.
2007 – Three terrorists suspected to be a part of Al-Qaeda are arrested in Germany after allegedly planning attacks on both the Frankfurt International airport and US military installations.
2020 – Pope Benedict XVI becomes the longest-lived pope, 93 years, four months, 16 days, surpassing Pope Leo XIII, who died in 1903.
2022 – Ten people are killed and 15 are injured in a stabbing spree in 13 locations on the James Smith Cree Nation and in Weldon, Saskatchewan.