Chinese boatmen in the Port at Lushunkou, a district in the municipality of Dalian, Liaoning province, also called Lushun City or Lushun Port, formerly known as both Port Arthur and Ryojun. During the Russo-Japanese war, the Russians surrendered Port Arthur to the Japanese after nearly a year's siege: the Japanese expended 58,000 killed or wounded to obtain the town. As can be seen here, Lushunkou boasts an excellent natural harbour, the possession and control of which became a 'casus belli' (justification for the act of war) during the Russo-Japanese War (1904?1905).