and became a Supreme War Councilor in 1912. He was further promoted to become the youngest field marshal in the Imperial Japanese Army in 1919. In 1921, he accompanied then-Crown Prince Hirohito on his tour of Europe. Career in the Imperial General Headquarters On December 1, 1931, Prince Kan'in became Chief of the Imperial Japanese Army General Staff, replacing General Kanaya Hanzo. During his tenure, the Imperial Japanese Army committed many war crimes against Chinese civilians including the Nanking massacre and the systemic use of chemical and bacteriological weapons. Chemical weapons, such as tear gas, were used only sporadically in 1937, but in the spring of 1938, the Imperial Japanese Army began full-scale use of sneeze and nausea gas (red), and from summer 1939, mustard gas (yellow) was used against both Kuomintang and Communist Chinese troops. Prince Kan'in transmitted to the Army the emperor's first directive (rinsanmei) authorizing the use of chemical weapons on July 28, 1937. He transmitted a second order on September 11 authorizing the deployment of special chemical warfare units to Shanghai. On April 11, 1938, Directive Number 11 was issued in his name, authorizing further use of poison gas in Inner Mongolia. Kan'in, among others within the army, opposed Prime Minister Yonai Mitsumasa's efforts to improve relations with the United States and the United Kingdom. He forced the resignation of War Minister General Hata Shunroku (1879–1962), thus bringing down the Yonai cabinet in July 1940. The Prince was a participant in the liaison conferences between the military chiefs of staff and the second cabinet of Prince Konoe Fumimaro (June 1940–July 1941). Both he and Lieutenant General Hideki Tojo, the newly appointed War Minister, supported the Tripartite Pact between the Empire of Japan, Nazi Germany, and Fascist Italy. Final years and death Kan'in retired as Chief of the General Staff on October 3, 1940 and was succeeded by Sugiyama Hajime. He remained a member of the Supreme War Council and a senior advisor to the emperor on army matters. Field Marshal Prince Kan'in died in Odawara, Kanagawa at the Kan'in summer residence, possibly due to an infection caused by inflamed hemorrhoids on May 21, 1945 and was accorded a state funeral. The Prince was a strong supporter of State Shinto; with Hiranuma Kiichirō he set up the Shintoist Rites Research Council to research all ancient Shinto rites and practices. Other associates were Kuniaki Koiso, Lieutenant General Heisuke