A newly reviewed wartime document shows that Japan’s Imperial Army secretly prepared for the possibility of imposing martial law in Tokyo in January 1945, amid fears that large-scale US air raids could cause widespread destruction and disrupt public order.
The document, dated 29 January 1945 and marked “Military Top Secret”, was prepared by the Eastern District Army, which was responsible for defending eastern Japan, including Tokyo. It outlined procedures for imposing martial law if repeated air raids caused severe disruption, potentially allowing the military to assume administrative authority and other powers. Martial law was never imposed.
The study was examined by Seishi Ishibashi, a curator at the Sumida Heritage Museum in Tokyo’s Sumida Ward, which researches wartime air-raid damage. The document is held by the Defence Ministry’s National Institute for Defence Studies and is titled “Study of Details of Martial Law Operations Based on Assumptions (Draft).”
The army’s scenarios significantly underestimated the scale of casualties that would result from the attacks that actually occurred. For an initial raid, the document assumed about 200 B-29 bombers would attack Tokyo before dawn, using a combination of bombs and incendiaries. Under the scenario, the army estimated 2,500 deaths, 25,000 injuries and 150,000 other victims.
The study then envisioned a second attack seven days later on the Keihin district stretching from Tokyo to Yokohama in Kanagawa Prefecture. It assumed as many as 500 medium-sized bombers and about 80 heavy bombers would attack in five waves over roughly four hours, beginning at 2.30 a.m. The projected Tokyo casualties were 11,250 deaths, 51,250 injuries and 557,000 other victims.
The combined death estimate for the two raids was more than 13,700 people. The Great Tokyo Air Raid of 10 March 1945, however, killed around 100,000 people, mainly in central Tokyo, in a single night.
The document also anticipated extensive disruption to civilian administration and essential services. It projected the destruction of ward government offices, police stations and elementary schools, as well as damage to munitions factories and firefighting facilities. Rail services could be suspended, while communications, electricity, gas and water supplies could be disrupted.
A third scenario covered the period of about 15 days after the second raid. It assumed recovery efforts by the Tokyo metropolitan government and other authorities would fail to proceed as planned, with roughly 80 per cent of temporary restoration work eventually completed “with the powerful support of the military in the end”.
The document also anticipated growing public defeatism, including what it described as self-destructive words and actions by residents. Enemy plots and an increase in letters critical of the military were identified as matters “requiring vigilance”. Under those circumstances, the Eastern District Army’s general staff was expected to conclude that martial law was unavoidable.
The document set out procedures for reporting the decision to Emperor Hirohito, posthumously known as Emperor Showa, following an emergency cabinet meeting. Under the Constitution of the Empire of Japan, declaring martial law was considered a sovereign prerogative of the Emperor.
“It appears that the scenarios were intended to verify procedures for imposing martial law. Yet during the actual Great Tokyo Air Raid, more than seven times as many people were killed in a single night,” Ishibashi said. “It was unrealistic, and we can only say its underlying assumptions were far too optimistic.”
The March 10 raid also marked a change in US bombing strategy, from high-altitude precision attacks focused mainly on munitions factories to carpet bombing using large quantities of incendiary bombs against densely packed wooden housing. The Japanese authorities had not anticipated that tactical shift.
