The Siege of Port Arthur (Japanese: 旅順攻囲戦, Ryojun Kōisen; Russian: Оборона Порт-Артура, Oborona Port-Artura, August 1, 1904 – January 2, 1905), the deep-water port and Russian naval base at the tip of the Liaodong Peninsula in Manchuria, was the longest and most violent land battle of the Russo-Japanese War.