<P> The Treaty of Portsmouth formally ended the 1904--05 Russo - Japanese War . It was signed on September 5, 1905 after negotiations lasting from August 6 to August 30, at the Portsmouth Naval Shipyard in Kittery, Maine, United States . U.S. President Theodore Roosevelt was instrumental in the negotiations, and won the Nobel Peace Prize for his efforts . </P> <P> The war of 1904--05 was fought between the Empire of Russia, an international power with one of the largest armies in the world, and the Empire of Japan, a nation which had only recently industrialized after two - and - a-half centuries of isolation . A series of battles in the Liaodong Peninsula had resulted in Russian armies being driven from southern Manchuria, and the Battle of Tsushima had resulted in a cataclysm for the Imperial Russian Navy . The war was unpopular with the Russian public, and the Russian government was under increasing threat of revolution at home . On the other hand, the Japanese economy was severely strained by the war, with rapidly mounting foreign debts, and its forces in Manchuria faced the problem of ever - extending supply lines . No Russian territory had been seized, and the Russians continued to build up reinforcements via the Trans - Siberian Railway . Recognizing that a long - term war was not to Japan's advantage, as early as July 1904 the Japanese government had begun seeking out intermediaries to assist in bringing the war to a negotiated conclusion . </P>

The peace conference ending the russo japanese war took place in which country