page_title: Kantokuen
section_title: The Hachi-Go plans
hierarchical_section_title: Kantokuen / Background / The Hachi-Go plans
caption_attribution_description: English: Outline of Concept B of the Hachi-Go Plan, a 1938-39 Japanese contingency for an invasion of the Soviet Union in 1943.
context_page_description: KANTOKUEN was an operational plan created by the General Staff of the Imperial Japanese Army for an invasion and occupation of the far eastern region of the Soviet Union, capitalizing on the outbreak of the Soviet-German War in June 1941. Involving seven Japanese armies as well as a major portion of the empire's naval and air forces, it would have been the largest single combined arms operation in Japanese history, and one of the largest of all time.
  The plan was approved in part by Emperor Hirohito on July 7 and involved a three-step readiness phase followed by a three-phase offensive to isolate and destroy the Soviet defenders in no more than six months. It envisioned heavy use of chemical and biological weapons. After growing conflict with simultaneous preparations for an offensive in Southeast Asia, together with the demands of the Second Sino-Japanese War and dimming prospects for a swift German victory in Europe, Kantokuen began to fall out of favor at Imperial General Headquarters and was eventually abandoned following increased sanctions by the United States and its allies in late July and early August 1941.
context_section_description: Independent of their yearly planning, in 1938–39 the Operations Bureau of the Japanese Army General Staff and the Kwantung Army cooperated on a pair of related contingencies under the umbrella term "Operational Plan no. 8," or the "Hachi-Go" plan. These two schemes, designated Concepts "A" and "B," examined the possibility of an all-out war with the Soviet Union beginning in 1943. Both were far larger than anything previously conceived of by the Japanese, envisioning a commitment of 50 IJA divisions against an expected 60 for the Soviets to be delivered incrementally from China and the Home Islands. Whereas Concept A followed a more traditional setup by calling for attacks in the East and North while holding in the West, Concept B examined the possibility of first striking out into the vast steppe between the Great Khingan Mountains and Lake Baikal in the hopes of scoring a knockout blow early – thus dooming the defenders of Primorye and Vladivostok to defeat in detail. The scope of operations was enormous: the two forces would have fought over a frontage nearly 5,000 kilometers (3,100 miles) in length, with Japan's final objectives being up to 1,200 km (750 mi) deep into Soviet territory. In terms of distances, Concept B of Hachi-Go would have dwarfed even Barbarossa, Nazi Germany's invasion of the USSR in June 1941.
  As impressive as this appeared on paper, however, the Japanese were forced to acknowledge several harsh realities blocking the implementation of Hachi-Go in the near future. Specifically with regard to Concept B, the railway network in Manchuria had not been sufficiently expanded to facilitate such a far-reaching offensive and supply stocks on hand in the country were seriously below the required levels. Furthermore, the ongoing war in China precluded the concentration of the planned 50 divisions without fatally weakening the Japanese effort there. Additionally, Imperial General Headquarters concluded that in order to sustain a drive out to Lake Baikal, a fleet of some 200,000 trucks would be necessary, a number more than twice as great as anything the entire Japanese military possessed at any given time. Popular support for Concept B in IJA circles dissipated in 1939 after the Battle of Khalkhin Gol demonstrated the extensive challenges of supplying a sustained military commitment on even a relatively limited scale so far away from the nearest rail heads. From that point forward, Japanese offensive planning vis-a vis the USSR was chiefly focused on the Northern and Eastern fronts, with any advances in the West being limited to relatively modest gains on the far slope of the Great Khingan range.
caption: Hachi-Go Concept B[23]
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