As in the First Sino-Japanese War, the Liaodong peninsula was the scene of major fighting in the Russo-Japanese War (1904–1905), including the bloody Siege of Port Arthur. As a consequence of the Treaty of Portsmouth (5 September 1905), which ended the Russo-Japanese War, both sides agreed to evacuate Manchuria and return it to China, with the exception of the Liaodong Peninsula leased territory which was transferred to Japan, which was to administer it as the Kwantung Leased Territory.