Question: The British Mandate for Palestine was finally confirmed in 1922, the civil Mandate administration was formalized with the League of Nations' consent in 1923 following the ratification of which peace treaty signed in Palais de Rumine?
Context: al-Najjada (Arabic: النجادة‎ ‎ , or "Munazzamat al-Najjada al-Falastiniyya") was a Palestinian Arab paramilitary scout movement formed in Jaffa, British Mandate of Palestine on 8 December 1945.  The organisation was headed by Muhammad Nimr al-Hawari as General Commander (al-Harawi had served in the British Mandate administration) and Rashad al-Dabbagh as Secretary General.  The al-Najjada HQ was on Railway Station Street Jaffa.  Its officers were mainly Arabs who had served in the British Army.  During the lead into the 1948 war its membership numbered 2,000 to 3,000 but the organisation lacked arms.  The Great revolt 1936-1939 led to an imbalance of power between the Jewish community and the Arab community, as the latter had been substantially disarmed.  The British had estimated al-Najjada strength as 8,000 prior to 1947. Mandatory Palestine (Arabic: فلسطين‎ ‎ "Filasṭīn "; Hebrew: פָּלֶשְׂתִּינָה (א"י)‎ "Pālēśtīnā (EY) ", where "EY" indicates "Eretz Yisrael", Land of Israel) was a geopolitical entity under British administration, carved out of Ottoman Southern Syria after World War I.  British civil administration in Palestine operated from 1920 until 1948.  During its existence the territory was known simply as "Palestine", but, in later years, a variety of other names and descriptors have been used, including "Mandatory" or Mandate Palestine, the British Mandate of Palestine and British Palestine. The List of post offices in the British Mandate of Palestine refers to post offices operated in Palestine under allied British military control of the Occupied Enemy Territory Administration and, after 1920, the civil administration of the British Mandate of Palestine.  During the Mandate, postal services were provided by British authorities. The Treaty of Lausanne (French: "Traité de Lausanne" ) was a peace treaty signed in Palais de Rumine, The British Mandate for Palestine, also known as the Mandate for Palestine or the Palestine Mandate, was a League of Nations mandate for the territory that had formerly constituted the Ottoman Empire sanjaks of Nablus, Acre, the Southern part of the Vilayet of Syria, the Southern portion of the Beirut Vilayet, and the Mutasarrifate of Jerusalem, prior to the Armistice of Mudros. The British Mandate for Palestine was finally confirmed in 1922 .  The civil Mandate administration was formalized with the League of Nations' consent in 1923 following the ratification of the Treaty of Lausanne. The U.S.—German Peace Treaty is a peace treaty between the U.S. and German governments, signed in Berlin on August 25, 1921, in the aftermath of World War I.  The main reason for the conclusion of that treaty was the fact that the U.S. Senate did not consent to ratification of the multilateral peace treaty signed in Versailles, thus leading to a separate peace treaty.  Ratifications were exchanged in Berlin on November 11, 1921, and the treaty became effective on the same day.  The treaty was registered in "League of Nations Treaty Series" on August 12, 1922. During the British Mandate over Palestine between 1920 and 1948, officially recognized by the League of Nations in the Palestine Mandate (July 24, 1922), the de facto flag was the Union Jack or Union Flag of the United Kingdom, but several localised flags existed for Mandate government departments and government officials.  The only Palestine-specific flag not restricted to official government use was the Palestine ensign (red with the Union Flag in the canton, and a white circle on the fly with the mandate's name inside it), which was flown by ships registered in the British Mandate territory from 1927 to 1948.  This flag had an extremely limited use on land and was not embraced by either the Arabs or the Jews of the Palestine mandate territory.  It was based on the British Red Ensign (civil ensign) instead of the Blue Ensign (used as the basis for the flags of nearly all other British-ruled territories in Africa and Asia) since it was intended for use only at sea by non-government ships. The following is a list of massacres that have occurred in Palestine prior to the establishment of the British Mandate for Palestine.  For massacres that took place prior to the name "Palestine" being adopted, see List of massacres in ancient Israel.  For massacres that took place in the British Mandate for Palestine, see List of killings and massacres in Mandatory Palestine.  For massacres that took place during the 1948 Palestine War, see Killings and massacres during the 1948 Palestine War.  For massacres that took place prior to the British Mandate, see List of massacres in Palestine.  For massacres that have occurred in Israel following its declaration of independence, see List of massacres in Israel.  For massacres that have occurred in the West Bank and the Gaza Strip since 1948, see List of massacres in Palestinian Territories. The List of postal rates in the British Mandate of Palestine are the postal rates in effect in Palestine under military occupation British and allied forces and later civil administration of the British Mandate of Palestine between 1917 and 1948.  During the Mandate, postal services were provided by British authorities.
Answer: Treaty of Lausanne