League of Nations mandates were territories established under Article 22 of the Covenant of the League of Nations, 28 June 1919. Upon the entry into force of the Charter of the United Nations in late 1945, the mandates of the League of Nations became United Nations Trust Territories, as agreed earlier in Yalta Conference.

All the territories subject to League of Nations mandates were previously controlled by states defeated in World War I, principally Imperial Germany and the Ottoman Empire. The mandates were fundamentally different from protectorates in that the Mandatory power undertook obligations to the inhabitants of the territory and to the League of Nations.

The process of establishing the mandates consisted of two phases:

1. the formal removal of sovereignty of the previously controlling states
2. the transfer of mandatory powers to individual states among the Allied Powers.

The exact level of control by the Mandatory power over each mandate was decided on an individual basis by the League of Nations. However, in every case the Mandatory power was forbidden to construction fortifications or raise an army within the mandate and was required to present an annual report on the territory to the League of Nations.

Despite this, mandates were seen as de facto colonies of the empires of the victor nations.

Class A mandates

The mandates were divided into three distinct groups based upon the level of development each population had achieved at that time.

The first group or Class A mandates were areas fomerly controlled by the Ottoman Empire deemed to "...have reached a stage of development where their existence as independent nations can be provisionally recognized subject to the rendering of administrative advice and assistance by a Mandatory..." The Class A mandates assigned to France were Syria and Lebanon; Iraq, Palestine, and Transjordan were assigned to Britain. By 1949 all of these mandates had been replaced by sovereign governments.

Class B mandates

The second group or Class B mandates which included the region of Central Africa were deemed to require a greater level of control by the mandatory power: "...the Mandatory must be responsible for the administration of the territory under conditions which will guarantee freedom of conscience and religion". The mandatory power was forbidden to construct military or naval bases within the mandates. The Class B mandate assigned to Belgium was Ruanda-Urundi; Togoland and the Cameroons were assigned in part to France and in part to Britain; Tanganyika was assigned to Britain.

Class C mandates

A final group, the Class C mandates, including South-West Africa and certain of the South Pacific Islands were considered to be "best administered under the laws of the Mandatory as integral portions of its territory"

The Class C mandates consisted of South West Africa which was administered by South Africa; former German Samoa assigned to New Zealand; New Guinea and Nauru assigned to Australia and the German islands in the Pacific north of the equator which were assigned to Japan as the Japanese Mandate of the Pacific Islands.

Treaties

Germany's divestiture of territories was accomplished in the Treaty of Versailles of 1919 and alloted to the Allied Powers on May 7, 1919. Ottoman territorial claims were first dispensed with in the Treaty of Sevres of 1920 and later finalized in the Treaty of Lausanne of 1923. The Turkish territories were alloted to the Allied Powers in the Conference of San Remo of 1920.

All of the former mandates are now independent states; the lasts mandate to gain independence were South West Africa which gained independence as Namibia in 1990 after a long war with South Africa.