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Russo-Japanese War
1904–1905· War· Wars & invasions
Well documentedSolid records, physical evidence or scientific consensus.
The 1904–05 war in which Japan defeated Russia for control of Korea and Manchuria, clearing the way to its protectorate over Korea.
See it on the Korean History map →What happened
The Russo-Japanese War (러일전쟁) grew from rivalry over Korea and Manchuria. In February 1904, despite Korea's declared neutrality, Japan attacked Russian ships at Port Arthur and Chemulpo (Incheon), landed troops in Korea and forced Seoul to allow military use of its territory. Japan won at Port Arthur, Mukden and the Tsushima Strait; well over 100,000 soldiers died on both sides, though estimates vary. In the Treaty of Portsmouth (September 1905), brokered by US President Theodore Roosevelt, Russia accepted Japan's "paramount" interests in Korea.
Why it matters
It removed Korea's last great-power counterweight to Japan; within three months Japan imposed the Eulsa protectorate treaty, with British and American acceptance.
How we know
Military and diplomatic archives of Japan, Russia, Britain and the US, the Portsmouth treaty text, and the February 1904 Japan–Korea Protocol.
Still debated
How explicit the 1905 Taft–Katsura understanding with the US was is debated, as is how inevitable annexation was after the war.
Connections (2)
▸Russo-Japanese War left Japan dominant over Korean EmpireWell documented
The connection
During the war Japan stationed troops in Korea and forced agreements placing Japanese advisers in its finance and foreign ministries. Victory and great-power acceptance let Japan impose the 1905 Eulsa treaty, taking over Korea's foreign affairs, then force Gojong's abdication (1907) and annexation (1910).
When and how
Korea, 1904–1910; the Japan–Korea Protocol of February 1904 and the Eulsa treaty of November 1905.
How we know
The treaty texts and Japanese, British and US diplomatic correspondence recognizing Japan's position in Korea.
Debates and open questions
Korean scholars dispute the legal validity of the 1905 and 1910 treaties; how inevitable annexation was after 1905 is debated.
▸Russo-Japanese War led to Eulsa Treaty (Japan–Korea Protectorate Treaty)Well documented
The connection
Victory over Russia removed Japan's last rival in Korea. The September 1905 Treaty of Portsmouth recognized Japan's 'paramount' interests there, and the US (Taft–Katsura memorandum, July 1905) and Britain (renewed alliance, August 1905) accepted Japanese control. Ten weeks after Portsmouth, Japan imposed the protectorate.
When and how
War in Manchuria and Korean waters, 1904–1905; peace signed at Portsmouth, New Hampshire, September 5, 1905; protectorate imposed in Seoul, November 17, 1905.
How we know
The Portsmouth treaty text, the Taft–Katsura memorandum, the 1905 Anglo-Japanese Alliance, and Japanese cabinet decisions planning a protectorate.
Debates and open questions
Whether the Taft–Katsura talk was a deliberate US trade-off, Korea for the Philippines, or just an informal exchange of views is still debated.