|Native name||由比 光衛|
November 27, 1860|
Tosa Province, Japan
|Died||September 18, 1940(aged 79)|
|Allegiance||Empire of Japan|
|Service/branch||Imperial Japanese Army|
|Years of service||1882-1923|
Born in the Tosa Domain on Shikoku island (present day Kōchi Prefecture), Yui graduated from the 5th class of the Imperial Japanese Army Academy in 1882 and 7th class of the Army Staff College in 1891. He was assigned to staff positions within the Imperial General Headquarters on graduation.
Serving as a staff officer during the First Sino-Japanese War and the Boxer Rebellion, Yui developed a reputation as a competent officer. Yui was sent as a military attaché to Great Britain from 1895-1899. On his return to Japan, he became Chief of Staff of the IJA 5th Division.
At the start of the Russo-Japanese War, Yui (now a colonel) was assigned to the Japanese Second Army as a Vice Chief of Staff under General Yasukata Oku. He distinguished himself at the Battle of Mukden as Chief of Staff of the IJA 8th Division.
After promotion to major general in 1907, Yui continued to serve under General Oku as chief of the Imperial Japanese Army General Staff's Operations Section, until his promotion to lieutenant general and promotion to commandant of the Army Staff College in 1914, remaining in this post through most of Japan's involvement during World War I.
Yui was subsequently named commander of the IJA 15th Division and the Guards Division before becoming Chief of Staff of the Siberian Expeditionary Army in 1918. The following year, Yui become a full general and was in command of the Japanese garrison at Tsingtao from 1919 until 1922.
Resigning from active duty in 1923, Yui lived in retirement until his death in 1940.
- Connaughton, Richard (1988). The War of the Rising Sun and the Tumbling Bear - A Military History of the Russo-Japanese War 1904-5. London: Cassell. ISBN 0-415-00906-5.
- Dupuy, Trevor N. (1992). Encyclopedia of Military Biography. I B Tauris & Co Ltd. ISBN 1-85043-569-3.
- Lone, Stewart (1994). Japan's First Modern War: Army and Society in the Conflict with China, 1894-1895. St. Martin's Press.