During World War II, a prisoner-of-war camp was established at Hanaoka Mine on December 1, 1944. The prisoners included Dutch captured in the Dutch East Indies, and many Americans and Australians after mid-May 1945. The civilians at the camp were from captured after the Battle of Wake Island, and were survivors of the Woosung POW Camp near Shanghai. They were sent to Tokyo 2D and 5B Kawasaki Shipyards in Yokohama on the "Nitta Maru" before having been sent to Hanaoka. Likewise, many Americans at Hanaoka came from POW camps in Taiwan on the "Melbourne Maru," and the Australians had previously been at the Naoetsu POW camp in Niigata Prefecture. In violation of the Geneva Convention, these Allied POWs were assigned to the Fujita-gumi Construction Company as slave laborers. Despite the dangerous working conditions, only six prisoners died at the camp; one was killed by being crushed by a barrel of food and relief supplies dropped on the camp by an American aircraft. The camp with its remaining 245 American and 45 Australian POWs was liberated on September 15, 1945.