Russo-Japanese War

The Russo-Japanese War was fought from 1904 to 1905 between the Russian Empire and Japan over rival imperial ambitions in Manchuria and Korea, beginning with a surprise Japanese naval attack on the Russian fleet at Port Arthur in February 1904. Japanese forces went on to besiege and capture Port Arthur, win a costly land victory at the Battle of Mukden, and then, in the war's decisive engagement, virtually annihilate Russia's Baltic Fleet after its long voyage around the world at the Battle of Tsushima in May 1905. The war ended with the Treaty of Portsmouth, negotiated in the United States and mediated by President Theodore Roosevelt, in which Russia ceded its lease on the Liaodong Peninsula and the southern half of Sakhalin Island to Japan and recognized Japanese influence in Korea. Japan's victory marked the first time in the modern era that an Asian power had decisively defeated a major European power in a large-scale war, a result that reverberated widely, encouraging nationalist and anti-colonial movements across Asia while contributing to unrest within Russia that fed into the Russian Revolution of 1905.