The New Zealand civil administration of Western Samoa, formally established in 1920 as a League of Nations Class C Mandate following the 1914 wartime occupation of German Samoa, and continued as a United Nations Trust Territory after 1946 (following the League's 1946 dissolution) until Samoan independence in 1962. Wikipedia treats the Mandate and Trust Territory periods as a single continuous administration under one article ('Territory of Western Samoa'), not as two separate polities. The period included the Mau movement, a non-violent Samoan independence movement (beginning as the earlier, more localized 'Mau a Pule' resistance on Savaii in the early 1900s), which culminated in the 'Black Saturday' shooting of unarmed marchers by New Zealand military police in Apia on 28 December 1929 (killing Mau leader Tupua Tamasese Lealofi III and others) and continued to press for independence through the 1930s, contributing to the eventual grant of independence in 1962.
Became independent as the sovereign state of Western Samoa on 1 January 1962, the first Pacific island nation to gain independence (renamed simply 'Samoa' in 1997 — see existing 'Samoa' record).
Standard account of the NZ Mandate/Trust Territory era and the Mau movement's role in achieving independence.
A recent Oxford history of liberal imperialism in German Samoa, covering the colony directly cited by this record.