The Mandate for Palestine takes effect, creating Mandatory Palestine.

The Mandate for Palestine was a League of Nations mandate for British administration of the territories of Palestine and Transjordan – which had been part of the Ottoman Empire for four centuries – following the defeat of the Ottoman Empire in World War I. The mandate was assigned to Britain by the San Remo conference in April 1920, after France's concession in the 1918 Clemenceau–Lloyd George Agreement of the previously agreed "international administration" of Palestine under the Sykes–Picot Agreement. Transjordan was added to the mandate after the Arab Kingdom in Damascus was toppled by the French in the Franco-Syrian War. Civil administration began in Palestine and Transjordan in July 1920 and April 1921, respectively, and the mandate was in force from 29 September 1923 to 15 May 1948 and to 25 May 1946 respectively.

Mandatory Palestine was a British geopolitical entity that existed between 1920 and 1948 in the region of Palestine, and after 1922, under the terms of the League of Nations' Mandate for Palestine.

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