Hayashi's first major command from 1918 to 1920 was as commanding officer of the IJA 57th Infantry Regiment, followed by a time in 1921 attached to the Technical Research Headquarters and as an acting Military Investigator. From 1921 to 1923 he was the head of the Preparatory Course at the Imperial Japanese Army Academy, followed by a time attached to the Inspectorate General of Military Training. From 1923 to 1924 he was the Japanese Army Representative to the League of Nations, followed by another stint attached to the Inspectorate General of Military Training from 1924 to 1925.
In 1925, Hayashi became the commanding Officer of the IJA 2nd Infantry Brigade. In 1926 he was made Commandant of the Tokyo Bay Fortress. In 1927, he became the Commandant of the Army War College, followed in 1928 as Deputy Inspector-General of Military Training. Finally in 1929 he became the General Officer Commanding the Imperial Guards Division.
In 1930, Lieutenant-General Senjūrō Hayashi, was made Commander in Chief of the Japanese Korean Army. On the day after the Mukden Incident on 19 September, he ordered the IJA 20th Division to split its force, forming the 39th Mixed Brigade. Acting without authorization by the Emperor or central government in Tokyo, Hayashi ordered the 39th Mixed Brigade to cross the Yalu River that same day into Manchuria. The Cabinet was forced to concede the point to the military afterwards and the movement of the 39th Mixed Brigade from Korea was authorized on 22 September.
From 1934 to 1935 Hayashi was Army Minister, and again member of the Supreme War Council from 1935 until his retirement the next year.
As Army Minister, Hayashi was a supporter of Major General Tetsuzan Nagata, who was Chief of Military Bureau and the leader of the Tōseiha faction within the Imperial Japanese Army.[according to whom?] The Tōseiha scored a victory in July 1935 when General Jinzaburō Masaki, one of the leaders of the Kōdōha faction was removed as Inspector General of Military Training. But Nagata was assassinated the next month (the Aizawa Incident). The struggle between the Tōseiha and Kōdōha factions continued below the surface of the government; and the war in North China carried on apace until February 1936.
Hayashi also happen to the president of Greater Japan Muslim League (大日本回教協会, Dai Nihon Kaikyō Kyōkai).[3]
Hayashi served as Prime Minister of Japan for a brief four-month period in 1937, where he tried to establish a cabinet that rose above the factional strife of the political parties. He later demanded that members of his cabinet renounce their party ties.[4] Later from 1940 to 1941, he was a Privy Councillor.[5] Hayashi suffered from an intracranial hemorrhage in January 1943 and died at his home of 4 February without regaining consciousness. He was posthumously awarded the Order of the Golden Kite (4th class) and the Order of the Paulownia Flowers.
Honours
From the corresponding article in the Japanese Wikipedia
Grand Cordon of the Order of the Sacred Treasure (1932)
Grand Cordon of the Order of the Rising Sun (1934)
Grand Cordon of the Order of the Rising Sun with Paulownia Flowers (1943; posthumous)