Key Historical Events. The island was discovered by Capt. Fearn in 1798, annexed by Germany in Oct. 1888, and surrendered to Australian forces in 1914. It was administered by the UK under a League of Nations mandate from 1920 until 1947, when the UN approved a trusteeship agreement with Australia, New Zealand and the UK as joint administering authorities. Independence was gained on 31 Jan. 1968.