Protectorate of New Guinea. The total population in the Northern Marianas portion of these islands was only 2,646 inhabitants around this time, with the ten most northerly islands being actively volcanic and thus mostly uninhabited. Japan, allied with the Entente Powers during World War I, seized all of Germany's colonial possessions in East Asia and Micronesia, including the Northern Mariana Islands, and held them through the end of the war. Under the terms of the Treaty of Versailles in 1919, Germany was stripped of all her colonies worldwide, including the Palau, Caroline, Northern Mariana and Marshall Islands. By international agreement, these were all placed into trusteeship under the management of League of Nations which assigned them to Japan as the Class C South Seas Mandate. During this time, Japan used some of the islands for sugarcane production, modestly increasing the population of a few of the islands. World War II The island chain saw significant fighting during World War II. Guam, a possession of the United States since 1898, was captured by Japan in an attack from the Northern Mariana Islands that began on the day of the Japanese attack on Pearl Harbor (December 8, 1941, the same time as the Pearl Harbor attack across the International Date Line). In 1944, the United States captured the Mariana Islands chain from Japan: the Northern Mariana Islands were desired by the U.S. as bombing bases to reach the Japanese mainland, with the invasion of Saipan being launched for that reason in June before the U.S. even moved to recapture Guam; a month later the U.S. recaptured Guam and captured Tinian. Once captured, Saipan and Tinian's islands were used extensively by the United States military as they finally put mainland Japan within a round-trip range of American B-29 bombers. In response, Japanese forces attacked the bases on Saipan and Tinian from November 1944 to January 1945. At the same time and afterwards, the United States Army Air Forces based on these islands conducted an intense strategic bombing campaign against the Japanese cities of military and industrial importance, including Tokyo, Nagoya, Osaka, Kobe, and others. Both the Enola Gay and the Bockscar (which dropped atomic bombs on Hiroshima and Nagasaki, respectively) flew their missions from Tinian's North Field. According to Werner Gruhl: "Mariana Island historians estimate that 10 percent of Guam's some 20,000 population were killed by violence, most by the Japanese Imperial Army