was a general in the early

Imperial Japanese Army The Imperial Japanese Army (IJA; , ''Dai-Nippon Teikoku Rikugun'', "Army of the Greater Japanese Empire") was the principal ground force of the Empire of Japan from 1871 to 1945. It played a central role in Japan’s rapid modernization during th ...

. He was the younger brother of General

Ōsako Naoharu was a general in the early Imperial Japanese Army. He was the older brother of General Ōsako Naomichi.Kowner, '' Historical Dictionary of the Russo-Japanese War'', p. 273. Biography Ōsako was born as the eldest son to Ōsako Shinzō, a samur ...

.Kowner, '' Historical Dictionary of the Russo-Japanese War'', p. 272-273.

Biography

Ōsako was born to a

samurai The samurai () were members of the warrior class in Japan. They were originally provincial warriors who came from wealthy landowning families who could afford to train their men to be mounted archers. In the 8th century AD, the imperial court d ...

family in

Satsuma Domain The , briefly known as the , was a Han system, domain (''han'') of the Tokugawa shogunate of Japan during the Edo period from 1600 to 1871. The Satsuma Domain was based at Kagoshima Castle in Satsuma Province, the core of the modern city of ...

(present day

Kagoshima Prefecture is a Prefectures of Japan, prefecture of Japan located on the island of Kyushu and the Ryukyu Islands. Kagoshima Prefecture has a population of 1,527,019 (1 February 2025) and has a geographic area of 9,187 Square kilometre, km2 (3,547 Square m ...

). He joined the fledgling Imperial Japanese Army in April 1871, and joined the 2nd class of the predecessor of the

Imperial Japanese Army Academy The was the principal officer's training school for the Imperial Japanese Army. The programme consisted of a junior course for graduates of local army cadet schools and for those who had completed four years of middle school, and a senior course f ...

from December 1875. While still a cadet, he was called to active service to fight against his fellow Satsuma clansmen in the

Satsuma Rebellion The Satsuma Rebellion, also known as the , was a revolt of disaffected samurai against the new imperial government of the Empire of Japan, nine years into the Meiji era. Its name comes from the Satsuma Domain, which had been influential in ...

. In February 1879, he was commissioned as a second lieutenant in artillery. From May 1886, he attended the Army Staff College, specializing in artillery. He was sent to Germany for further training from May 1888. After his return to Japan, Ōsako was assigned to the Koishikawa Arsenal. He returned to Germany as a

military attache A military, also known collectively as armed forces, is a heavily Weapon, armed, highly organized force primarily intended for warfare. Militaries are typically authorized and maintained by a sovereign state, with their members identifiable ...

, remaining until July 1893. Ōsako was appointed battalion commander in the IJA 1st Field Artillery Regiment in February 1894. With the start of the

First Sino-Japanese War The First Sino-Japanese War (25 July 189417 April 1895), or the First China–Japan War, was a conflict between the Qing dynasty of China and the Empire of Japan primarily over influence in Joseon, Korea. In Chinese it is commonly known as th ...

, he was assigned to the staff of the

Japanese First Army The was an army of the Imperial Japanese Army. It was raised and demobilized on three occasions. History The Japanese 1st Army was initially raised during the First Sino-Japanese War from 1 September 1894 – 28 May 1895 under the command of ...

. After the end of the war, from October 1896, he was chief-of-staff of the IJA 5th Infantry Division and was promoted to colonel in October 1897. In December 1898, he became chief-of-staff of the IJA 4th Infantry Division. In June 1901, Ōsako was promoted to major general and commander of the IJA 2nd Field Artillery Brigade. With the start of the

Russo-Japanese War The Russo-Japanese War (8 February 1904 – 5 September 1905) was fought between the Russian Empire and the Empire of Japan over rival imperial ambitions in Manchuria and the Korean Empire. The major land battles of the war were fought on the ...

, Ōsako participated in the

Siege of Port Arthur The siege of Port Arthur (, ''Ryojun Kōisen''; , ''Oborona Port-Artura'', August 1, 1904 – January 2, 1905) was the longest and most violent land battle of the Russo-Japanese War. Port Arthur, the deep-water port and Russian naval base ...

. He was appointed chief-of-staff of the

Japanese Second Army The was an army of the Imperial Japanese Army. It was raised and demobilized on four occasions. History The Japanese 2nd Army was initially raised during the First Sino-Japanese War from September 27, 1894, to May 14, 1895, under the command o ...

from September 1904. After the end of the war, Ōsako was awarded the

Order of the Golden Kite Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * ...

, 2nd class, and was reassigned to the

Inspectorate General of Military Training The was a section of the Imperial Japanese Army charged with military education and training in the army, except military aviation training. It was headed by an inspector general who was responsible for overseeing technical and tactical training, ...

from February 1906. He was promoted to lieutenant general in November 1907 and from November 1910 was the commander of the IJA 18th Infantry Division and from December 1912 was commander of the IJA 4th Infantry Division. In May 1914, Ōsako was awarded the Grand Cordon of the

Order of the Sacred Treasure The is a Japanese Order (distinction), order, established on 4 January 1888 by Emperor Meiji as the Order of Meiji. Originally awarded in eight classes (from 8th to 1st, in ascending order of importance), since 2003 it has been awarded in six c ...

. From February 1915, he served on the

Supreme War Council The Supreme War Council was a central command based in Versailles that coordinated the military strategy of the principal Allies of World War I: Britain, France, Italy, the United States, and Japan. It was founded in 1917 after the Russian Revolu ...

and was promoted to general in August 1915. In November 1918, he was awarded the

Order of the Rising Sun The is a Japanese honors system, Japanese order, established in 1875 by Emperor Meiji. The Order was the first national decoration awarded by the Japanese government, created on 10 April 1875 by decree of the Council of State. The badge feat ...

, 1st class. In July 1919, he transferred to the reserves. His grave is at the

Tama Cemetery in Tokyo is the largest municipal cemetery in Japan. It is split between the cities of Fuchū, Tokyo, Fuchu and Koganei, Tokyo, Koganei within the Tokyo Metropolis. First established in April 1923 as , it was redesignated Tama Cemetery in 1935. ...

in Tokyo.