The Mandate for Syria and Lebanon takes effect.

The Mandate for Syria and the Lebanon was a League of Nations mandate founded in the aftermath of the First World War and the partitioning of the Ottoman Empire, concerning the territories of Syria and Lebanon. The mandate system was supposed to differ from colonialism, with the governing country intended to act as a trustee until the inhabitants were considered eligible for self-government. At that point, the mandate would terminate and a sovereign state would be born.

September 29 is the 272nd day of the year in the Gregorian calendar; 93 days remain until the end of the year.