The Battle of Port Arthur (Japanese: 旅順口海戦, Hepburn: Ryojunkō Kaisen) of 8–9 February 1904 (Monday February 8 - Tuesday February 9) marked the commencement of the Russo-Japanese War. It began with a surprise night attack by a squadron of Japanese destroyers on the Russian fleet anchored at Port Arthur, Manchuria, and continued with an engagement of major surface combatants the following morning; further skirmishing off Port Arthur would continue until May 1904.