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The Japanese 20th Army was formed on September 10, 1941 under the Kwantung Army in Heilongjiang province in northern Manchukuo as a garrison and border patrol force. It came under the administrative control of the Japanese First Area Army on July 4, 1942. On October 19, 1944, it was transferred to central China and came under the command of the Japanese Sixth Area Army to provide a garrison force for areas left under defended by the movement of troops further south in Operation Ichi-Go. From April 9, 1945 - June 7, 1945 it carried out the offensive in the Battle of West Hunan, the last major Japanese offensive of the Second Sino-Japanese War, during which time it suffered significant casualties. After the surrender of Japan, the 20th Army came under control of the Kuomintang government of the Republic of China and was assigned to the maintenance of public order until it was officially disbanded on July 15, 1946 at Hengyang, Hunan province.
Hsu Long-hsuen, and Chang Ming-kai. History of the Sino Japanese War (1937-1945). 2nd ed. Taipei, Taiwan, Republic of China: Chung Wu Publishing Co., 1972. p. 457