The Kwantung Army's defeat in Manchuria helped lead to Japan's surrender in August 1945.
The Soviet Union invaded Japanese-occupied Manchuria beginning on 9 August 1945. Soviet and Mongolian forces rapidly overwhelmed the Kwantung Army, Japan's major formation in the region, and seized key territory in Manchuria and northern Korea.
Japan's leaders had hoped the Soviet Union might mediate between Japan and the Western Allies. The Soviet attack destroyed that possibility and added a powerful military shock alongside the atomic bombings of Hiroshima and Nagasaki.
The Kwantung Army had once been regarded as an elite force, but by 1945 many experienced units and weapons had been transferred to other fronts. Its defeat was therefore swift, although scattered fighting continued and the army's surrender was not immediately accepted everywhere.