history of New Zealand By nanomir Sep 26, 1907 New Zealand became a dominion of Britain Jul 28, 1914 _ Period: Jul 28, 1914 to Nov 11, 1918 New Zealand's participation in World War I. Dec 17, 1920 New Zealand received a mandate to govern Western Samoa and Nauru. Nov 11, 1931 of the Statute of Westminster country gained full independence. Period: Sep 1, 1939 to Sep 2, 1945 New Zealand's participation in World War 2 Period: Jun 25, 1950 to Jul 27, 1953 New Zealand's participation in the Korean War Period: Mar 2, 1965 to Dec 31, 1967 New Zealand participated in the Vietnam War