Education
Yasuoka was a native of Kagoshima Prefecture, and graduated from the 18th class of the Imperial Japanese Army Academy in 1906 and from the 26th class of the Army Staff College in 1914.
安岡 正臣
Yasuoka was a native of Kagoshima Prefecture, and graduated from the 18th class of the Imperial Japanese Army Academy in 1906 and from the 26th class of the Army Staff College in 1914.
After serving in a number of staff positions, he was assigned to the IJA 51st Infantry Regiment, rising to become its commander by 1922. In 1935, Yasuoka was promoted to major general and given command of the IJA 30th Infantry Brigade. After having served two years (1936 and 1937) as Commandant of the Armored Warfare School, Yasuoka was promoted to lieutenant general and was made commander of the IJA 1st Independent Mixed Brigade.
With the start of the Second Sino-Japanese War, Yasuoka"s expertise in armored warfare was recognized when he was made commander of the Yasuoka Detachment, an armored task force of the Kwantung Army, organized for the Japanese July 1939 offensive of the Battle of Khalkhin Gol.
However, the Japanese army suffered a ruinous defeat at the hands of the combined Soviet-Mongolian forces and Yasuoka was relieved of command on 9 July 1939 and his detachment was dissolved. Yasuoka was assigned command of the 3rd Depot Division to 1941, whereupon he resigned from the Army and officially retired.
In 1942, Yasuoka agreed to accept the post of military-governor of Surabaya in Japanese-occupied Java, Netherlands East Indies. He held the post until the surrender of Japan in August 1945, whereupon he was arrested by Dutch authorities and tried before a military tribunal for war crimes.
He was condemned to death and hanged on 12 April 1948.