The Kwantung Army surrendered in Manchuria on August 16, 1945, after Japan announced its surrender.
The Kwantung Army was the principal Japanese force defending Manchukuo, the Japanese-established puppet state in Manchuria. The Soviet Union invaded Manchuria beginning on August 9, attacking Japanese positions from several directions with a large, experienced force.
Japan’s surrender announcement came on August 15, but fighting did not stop everywhere immediately. The Kwantung Army officially surrendered on August 16, while some combat continued until the formal surrender ceremony on September 2.
The Kwantung Army had once been regarded as one of Japan’s strongest formations, but by 1945 many experienced units and weapons had been transferred to other fronts. Its rapid defeat by Soviet forces was one of the major military shocks surrounding Japan’s decision to surrender.