• Chief of Staff of the Imperial Japanese Navy Admiral Shigetarō Shimada, 1883
• Chief of Staff of the Imperial Japanese Navy Admiral Koshirō Oikawa, 1883

 

A native of Tokyo, Shimada graduated from the 32nd class of the Imperial Japanese Naval Academy in 1904. He was ranked 27th out of 192 cadets, and one of his classmates was the famous admiral Isoroku Yamamoto.

Shimada served his midshipman duty aboard the submarine tender Karasaki, and the cruiser Izumi, participating in the Battle of Tsushima during the Russo - Japanese War.

After commissioning as a sub-lieutenant, he was assigned to the cruisers Niitaka and Otowa. After his promotion to lieutenant on 11 October 1909, he served on the battlecruiser Tsukuba and battleship Settsu.

After graduating with highest honors from the Naval War College in December 1913, Shimada was promoted to lieutenant commander in December 1915 and assigned as an assistant naval attaché in Rome, Italy during World War I.

Returning to Japan after the war, Shimada held various staff positions in the 1920s as a staff officer the Imperial Japanese Navy General Staff in 1920, executive officer of the battleship Hyūga in 1922, an instructor at the Naval War College in 1923 and commander of the 7th Submarine Division in 1926.

He was promoted to captain on 1 December 1924, and his first command was the cruiser Tama in 1928, followed by the battleship Hiei later the same year.

Shimada was promoted to rear admiral on 30 November 1929, and assigned as Chief of Staff to the IJN 2nd Fleet. After Shimada was transferred to IJN 1st Fleet in December 1930, he served as Commandant of the Submarine School, before being assigned to the IJN 3rd Fleet in February 1932. As commander of the IJN 3rd Fleet, he participated in the First Shanghai Incident of 1932.

Returning to the Imperial Japanese Navy General Staff as a senior staff officer in June 1932, he served as Chief of the Third and later served concurrently as Chief of the First Department from November 1932-October 1933 when he assumed total command. Becoming Vice Chief of the Naval General Staff in December 1933, Shimada was promoted to vice admiral on 15 November 1934.

During the late-1930s Shimada's positions included commandant of the Kure Naval District, commander in chief of the IJN 2nd Fleet and China Area Fleet as well as commanding officer of the Yokosuka Naval District.

Shimada was named Minister of the Navy on 18 October 1941. During his term as Navy Minister, he knew of the plans for the attack on Pearl Harbor and approved its implementation. Although largely regarded as a submissive lackey for his reputation of meek submissiveness and unquestioning loyalty to Prime Minister Hideki Tōjō (which created considerably unpopularity and criticism among his naval associates, who would refer to him as "Tōjō's Yurufun" ("Tōjō's Droopy Drawers"), Tōjō's "tea servant" or "briefcase carrier" behind his back), Shimada played an important role in working with Tōjō in coordinating military operations between the Army and Navy during the early years of the Pacific War.

After a series of major Japanese losses, Emperor Hirohito lost confidence in both the Army and Naval Chiefs of Staff. As such, Tōjō was able to dismiss Chief of the Army General Staff Hajime Sugiyama and Chief of the Naval General Staff Osami Nagano. Tōjō assumed the role of Army Chief of Staff while Shimada became Naval Chief of Staff on 21 February 1944, concurrent with his position as Naval Minister. This reorganization made Shimada supreme commander of the Imperial Japanese Navy.

Shimada's power grab, however, gained him many enemies in the Navy General Staff and the Emperor's court. Shimada's opponents continuously pressured Emperor Hirohito to dismiss him, citing that the navy was losing battle after battle under Shimada's direction. Hirohito finally made his displeasure with Shimada known to Tōjō in July 1944, shortly after the fall of Saipan. Tōjō immediately asked for Shimada's resignation, and replaced him as Navy Minister with Mitsumasa Yonai on 17 July and as Chief of the General Navy Staff on 2 August.

Although appointed to the Supreme War Council, Shimada retired from active duty on 20 January 1945 remaining in an advisory capacity for the remainder of the war.

After the war, Shimada was arrested by the SCAP authorities and charged with war crimes. At the International Military Tribunal for the Far East, he was convicted and sentenced to life imprisonment for waging aggressive war against the United States, United Kingdom, China and The Netherlands. After the end of the American occupation of Japan, he was released on parole in 1955 by Prime Minister Ichirō Hatoyama.

Oikawa was born into a wealthy family in rural Koshi County, Niigata Prefecture, but was raised in Morioka city, Iwate prefecture in northern Japan.

He was a graduate of the 31st class of the Imperial Japanese Naval Academy, ranking 76th out of 188 cadets. As a midshipman, he served on the cruisers Itsukushima and Izumo. During the Russo - Japanese War, still as a midshipman, he served on the Chiyoda during the Battle of Tsushima.

As a lieutenant, Oikawa served on the cruiser Katori, and the battleship Mikasa. He was given his first command, the destroyer Asashio on 28 April 1911. He subsequently served on the Yugiri, before attending the Naval Staff College in 1914.

On graduation, Oikawa was promoted to lieutenant commander, and was appointed aide - de - camp to Crown Prince Hirohito from 1915 - 1922.

After his promotion to captain on 1 December 1923, Oikawa was assigned the cruiser Kinu, followed by the Tama the following year. He then served in a number of staff positions until his promotion to rear admiral on 10 December 1928. In 1930, Oikawa was appointed to the Imperial Japanese Navy General Staff, and in 1932 became Director of the Imperial Japanese Naval Academy. He was promoted to vice admiral on 15 November 1933. Oikawa strongly supported the London Naval Treaty while a member of the Imperial Japanese Navy General Staff, and was thus a member of the Treaty Faction within the navy.

Oikawa was subsequently appointed Commander in Chief of the IJN 3rd Fleet (1935), Imperial Japanese Navy Aviation Bureau (1936), China Area Fleet (1938) and Yokosuka Naval District (1940). He was promoted to full admiral on 15 November 1939.

Oikawa was appointed as Minister of the Navy in the second and third cabinets of Prime Minister Fumimaro Konoe between 5 September 1940 and 18 October 1941. While Navy Minister, he strove to maintain ties with the United States, and instructed his naval attachés in Washington DC to work together with the Japanese ambassador to prevent war from breaking out. Likewise, he strongly opposed suggestions that Japan should declare war on the Soviet Union in early 1941.

He continued to serve as Naval Councilor to near the end of World War II and was Chief of the Navy General Staff in late 1944. He resigned in protest in May 1945 over Emperor Hirohito's refusal to consider peace proposals at a time when the war was clearly already lost. Oikawa retired from active duty on 5 September 1945.