I know Germany held colonial territories in that region through the late 19th century. However, I have never heard of German involvement in defending their land in the Pacific Theatre of the War, so am curious. All responses are appreciated!
Germany was stripped of all of its colonies in the Treaty of Versailles (Article 22), including those in the Pacific. The German island possessions (the Marshall, Caroline, Marianas minus Guam and Palau island groups) north of the Equator were transferred to Japan, and those south of the equator to Australia (German New Guinea), New Zealand (German Samoa) and joint British/Australia/New Zealand control(Nauru).
All were under Class C League of Nations mandates, "best administered under the laws of the Mandatory as integral portions of its territory", with the exception of the German concession at Tsingtao which was eventually returned to China in 1922 after tensions between Japan and China were mediated.
The Japanese and Australians occupied all of Germany's colonies in the Pacific in 1914. The League of Nations gave Mandates to Japan and Australia for the German colonies they occupied. With the exception of the German concession at Tingstao, which was restored to China, after Great Britain and the United States supported China when Japan issued their "21 Demands" on China. This was worked out in the wake of the Washington Treaty of Naval Limitations of 1922, the end of the Anglo Japanese Alliance and an agreement that Great Britain and the US would not fortify any of their bases east of Singapore and the Philipines, north of Australia or west of Oahu.