October 10, 1880|
Osaka prefecture, Japan
|Died||October 11, 1950 70)(aged|
|Allegiance||Empire of Japan|
|Service/branch||Imperial Japanese Army|
|Years of service||1909 -1945|
|Commands held||IJA 56th Division, IJA 32nd Army|
|Battles/wars||World War II|
Order of the Sacred Treasures (1st class)|
Order of the Rising Sun (1st class)
Watanabe was the son of a former samurai retainer of the Kishiwada domain. His father was an elementary school teacher. Watanabe was a graduate of the 21st class of the Imperial Japanese Army Academy in 1909, and of the 31st class of the Army Staff College in 1919, with a specialty in artillery.
From 1928 - 1933, Watanabe was an instructor of the Army Field Artillery School. He was assigned a commander of the IJA 10th Field Artillery Regiment from 1933–1936, after which he became Chief of Staff of the IJA 14th Division.
Before the start of the Second Sino-Japanese War, Watanabe was promoted to major general and was Chief of Staff of the Central Defense Army in Japan. He was reassigned to an administrative role when he became head of the Army Armaments Factory from 1938-1940. He was promoted to lieutenant general in 1939.
Under Watanabe, the 56th Division participated in the invasion of Burma. After landing at Rangoon, the 56th Division raced north and engaged Kuomingtang Chinese forces at the battle of Toungoo. After taking the city, the 56th Division flanked the Allied line to the east, by advancing through the mountains to the Salween River in the Karenni States. The 56th Division then defeated the Chinese 6th Corps in a number of small engagements and forced their retreat eastward into Yunnan. Advancing north through the Shan States the 56th Division defeated the Chinese 65th Corps to take the city of Lashio on the Burma Road. The 56th Division then advanced into Yunnan in pursuit of the Chinese forces but halted at the Salween River.
Following this success in combat, Watanabe was recalled to Japan, and from 1942–1944, was Commandant of the Army School of Science. However, with the war situation rapidly deteriorating against Japan, he was sent to the field again in 1944 as the first commander in chief of the newly formed IJA 32nd Army, tasked with the defense of the Ryukyu Islands.
Watanabe was recalled to Tokyo later the same year, and retired from military service. In the final stages of the war, he was recalled to duty, and assigned as commander of the Osaka region for the expected American invasion of the Japanese home islands. He was awarded with the Order of the Rising Sun, 1st class, just before the surrender of Japan. He died in 1950. His son, Akio Watanabe (born August 13, 1932) is currently a scholar and a politician.
- Fuller, Richard (1992). Shokan: Hirohito's Samurai. London: Arms and Armor. ISBN 1-85409-151-4.
- Louis, Allen (1984). Burma: The longest War. Dent Publishing. ISBN 0-460-02474-4.
- Hsu, Long-hsuen; Chang Ming-kai (1971). History of The Sino-Japanese War (1937-1945) 2nd Ed. Taiwan Republic of China: Chung Wu Publishing.
- Ammenthorp, Steen. "Watanabe Masao". The Generals of World War II.
- Budge, Kent. "Watanabe Masao". Pacific War Online Encyclopedia.