The Japanese 6th Army was initially raised on August 4, 1939 in Manchukuo as a garrison force to guard the western borders against possible incursions by the SovietRed Army. It was a major participant in the Nomonhan Incident, during which time it took severe casualties. Afterwards, it was initially assigned to Hailar, in Inner Mongolia which was also the site of an extensive Japanese static military fortification system. During much of the Second Sino-Japanese War, it remained a reserve and training garrison force.
On January 26, 1945, the Japanese Sixth Army was re-assigned to the control of the China Expeditionary Army, and was sent south to bolster Japanese forces in the strategic Wuhan-Changsha front, filling the gap left by the departure of Japanese forces in the southward Operation Ichi-Go thrust. At the surrender of Japan, it was disbanded at Hangzhou, Zhejiang province, China.
