This series of detailed topographic maps shows ten islands in the Pacific Ocean: nine in the Gilbert Islands chain and the separate island of Nauru. At the time these maps were made, the Gilbert Islands were part of the British colony of the Gilbert and Ellice Islands. Nauru, a former German colony, was a League of Nations protectorate administered by Australia, the United Kingdom, and New Zealand. Japan captured and occupied all of these islands during World War II. The maps appear to be of English origin, with detailed annotations subsequently added in Japanese. The maps show relief by shading and water depth by soundings, as well as provide information about navigation, population and settlements, and physical infrastructure. The maps were classified as "Military-Very Secret" and "Military-Secret" by the Japanese authorities. In 1979, the Gilbert Islands became the major part of the independent country of Kiribati. Nauru became an independent country in 1968.