The Dutch East Indies campaign of 1941–42 was the conquest of the Dutch East Indies (Indonesia) by forces from the Empire of Japan in the early days of the Pacific Campaign of World War II. Forces from the Allies attempted unsuccessfully to defend the islands. Indonesia was targeted by the Japanese for its rich oil resources which would become a vital asset during the war. The campaign and subsequent three and a half year Japanese occupation was also a major factor in the end of Dutch colonial rule in Indonesia.