# 30 September 1941 – World War II: The Babi Yar massacre comes to an end.
# 29 September 1972 – China–Japan relations: Japan establishes diplomatic relations with the People's Republic of China after breaking official ties with the Republic of China.
# 28 September 1995 – Israeli Prime Minister Yitzhak Rabin and PLO Chairman Yasser Arafat sign the Interim Agreement on the West Bank and the Gaza Strip.
# 27 September 1998 – The Google internet search engine retroactively claims this date as its birthday.
# 26 September 1815 - The Holy Alliance (German: Heilige Allianz; Russian: Священный союз, Svyashchennyy soyuz; also called the Grand Alliance) was a coalition created by the monarchist great powers of Russia, Austria and Prussia. It was created after the ultimate defeat of Napoleon at the behest of Tsar Alexander I of Russia and signed in Paris.
# 25 September 1969 - Organisation of Islamic Cooperation (OIC; Arabic: منظمة التعاون الإسلامي; French: Organisation de la coopération islamique) is an international organization founded.
# 24 September 2014 – The Mars Orbiter Mission makes India the first Asian nation to reach Mars orbit, and the first nation in the world to do so in its first attempt.
# 23 September 2002 – The first public version of the web browser Mozilla Firefox ("Phoenix 0.1") is released.
# 22 September 1948년 - 대한민국 친일파 단죄를 위한 반민족행위처벌법 공포.
# 21 September 1942 – The Holocaust in Ukraine: On the Jewish holiday of Yom Kippur, Nazis send over 1,000 Jews of Pidhaitsi to Bełżec extermination camp.
# 20 September 1946 – The first Cannes Film Festival is held, having been delayed seven years due to World War II.
# 19 September 634 – Siege of Damascus: The Rashidun Arabs under Khalid ibn al-Walid capture Damascus from the Byzantine Empire.
# 18 September 2018 - The September 2018 inter-Korean summit was the third inter-Korean summit in 2018.
# 17 September 1988 – The 1988 Summer Olympics are opened in Seoul, South Korea.
# 16 September 1992 – Black Wednesday: The British pound is forced out of the European Exchange Rate Mechanism by currency speculators and is forced to devalue against the German mark.
# 15 September 1894 – First Sino-Japanese War: Japan defeats Qing dynasty China in the Battle of Pyongyang.
# 14 September 1917 – The Russian Empire is formally replaced by the Russian Republic.
# 13 September 1971 – Chairman Mao Zedong's second in command and successor Marshal Lin Biao flees the People's Republic of China after the failure of an alleged coup. His plane crashes in Mongolia, killing all aboard.
# 12 September 1940 – Cave paintings are discovered in Lascaux, France.
# 11 September 2001 – The September 11 attacks, a series of coordinated suicide attacks killing 2,996 people using four aircraft hijacked by 19 members of al-Qaeda. Two aircraft crash into the World Trade Center in New York City, a third crashes into The Pentagon in Arlington County, Virginia, and a fourth into a field near Shanksville, Pennsylvania.
# 10 September 2002 – Switzerland, traditionally a neutral country, becomes a full member of the United Nations.
# 09 September 1948 – Kim Il-sung declares the establishment of the Democratic People's Republic of Korea (North Korea).
# 08 September 1966 – The landmark American science fiction television series Star Trek premieres with its first-aired episode, "The Man Trap".
# 07 September 1923 – The International Criminal Police Organization (INTERPOL) is formed.
# 06 September 1620 – The Pilgrims sail from Plymouth, England on the Mayflower to settle in North America. (Old Style date; September 16 per New Style date.)
# 05 September 1969 – My Lai Massacre: U.S. Army Lieutenant William Calley is charged with six specifications of premeditated murder for the death of 109 Vietnamese civilians in My Lai.
# 04 September 1999년 - 한국방송공사의 공개 코미디 프로그램 개그콘서트 첫방송.
# 03 September 1783 – American Revolutionary War: The war ends with the signing of the Treaty of Paris by the United States and the Kingdom of Great Britain.
# 02 September 1945 – Vietnam declares its independence, forming the Democratic Republic of Vietnam.
# 01 September 1951 – The United States, Australia and New Zealand sign a mutual defense pact, called the ANZUS Treaty.