1886–1948
✕ Died after postwar war-crimes arrest
The Japanese general whose armored command exposed the limits of Japan's tank doctrine
On 9 July 1939, after losing more than half its tanks, the Yasuoka Detachment was dissolved and he was relieved of command.
Yasuoka Masaomi was a lieutenant general of the Imperial Japanese Army who commanded tanks within an army still organized around infantry. At Khalkhin Gol in 1939, he led the improvised Yasuoka Detachment, built around the 1st Tank Corps, in the July offensive; poor coordination among tanks, infantry and artillery contributed to the loss of more than half its armor and the unit's dissolution. He later entered the reserve, served in Japan's occupation administration in Indonesia, and was arrested after the war on war-crimes charges before dying in 1948.
Activities and affiliations
Career Timeline
- 1906Second lieutenant, 43rd Infantry Regiment
- 1914Graduated from the Army War College
- 1935Major general; commander, 30th Infantry Brigade
- 1938Lieutenant general; commander, 1st Independent Mixed Brigade
- 1939Commander, 1st Tank Corps; led the Yasuoka Detachment at Khalkhin Gol
- 1941Transferred to the reserve
- 1942–1945Army administrative official; governor of Surabaya
- 1945–1948Arrested after the war on war-crimes charges; died in 1948
Related historical events
Command of the armored detachment at Khalkhin Gol
In July 1939, the Kwantung Army organized the Yasuoka Detachment as part of an offensive intended to encircle Soviet-Mongolian forces at Khalkhin Gol. Yasuoka commanded a force built around the 3rd and 4th Tank Regiments, with attached infantry, artillery, and engineers. The overall offensive force numbered about 15,000 men, with 87 tanks, 116 artillery and antitank guns, and 180 aircraft. Under the plan, the detachment was to attack south along the east bank of the Khalkhin Gol and link up with Japanese forces on the west bank. At dawn on July 3, its 87 tanks attacked the Soviet 149th Infantry Regiment and initially scattered the defenders, but Soviet artillery and tanks halted the advance. Japan’s Type 89 medium tanks were vulnerable to Soviet 45mm guns; in one engagement, the Soviet 9th Mechanized Brigade destroyed 20 of them. With the tanks failing to coordinate with attached infantry, engineers, and artillery, the detachment lost more than half its armor. On July 9 it was dissolved, Yasuoka was relieved of command, and the tank regiments were withdrawn. The defeat reflected both the failure to coordinate the tanks with other arms and Japanese intelligence’s underestimation of enemy strength.