The League of Nations Mandate for Palestine went into effect on September 29, 1923, granting the United Kingdom administrative control of Palestine. It also directed the UK to facilitate the creation of a Jewish state in the region pursuant to the 1917 Balfour Declaration. Learn more about the British Mandate for Palestine.

On September 29, 1983, Congress invoked the War Powers Act for the first time, authorizing President Ronald Reagan to keep US Marines in Lebanon for another 18 months.

On September 29, 1954, twelve European nations signed a convention, creating the European Organization for Nuclear Research (CERN). The laboratory was later constructed in Geneva, Switzerland. Learn more about the history of CERN.