page_title: Air raids on Japan
section_title: Pre-war Japanese defenses
hierarchical_section_title: Air raids on Japan / Background / Pre-war Japanese defenses
caption_attribution_description: English: Construction of Air-raid shelter in Japan 日本語: 日本における防空壕の建造
context_page_description: Allied forces conducted many air raids on Japan during World War II, causing extensive destruction to the country's cities and killing between 241,000 and 900,000 people. During the first years of the Pacific War these attacks were limited to the Doolittle Raid in April 1942 and small-scale raids on military positions in the Kuril Islands from mid-1943. Strategic bombing raids began in June 1944 and continued until the end of the war in August 1945. Allied naval and land-based tactical air units also attacked Japan during 1945.
  The United States military air campaign waged against Japan began in earnest in mid-1944 and intensified during the war's last months. While plans for attacks on Japan had been prepared prior to the Pacific War, these could not begin until the long-range B-29 Superfortress bomber was ready for combat. From June 1944 until January 1945, B-29s stationed in India staged through bases in China to make a series of nine raids on targets in western Japan, but this effort proved ineffective. The strategic bombing campaign was greatly expanded from November 1944 when bases in the Mariana Islands became available as a result of the Mariana Islands Campaign.
context_section_description: The Japanese government's pre-war plans to protect the country from air attack focused on neutralizing enemy air bases. Before the war it was believed that Soviet aircraft based in the Russian Far East posed the greatest threat. The Japanese military planned to destroy the air bases within range of the home islands if Japan and the Soviet Union ever went to war. When the Pacific War began, the Japanese government believed that the best way to prevent American air raids was to capture and hold the areas in China and the Pacific from which such attacks could be launched. It was expected that the Allies would not be able to re-capture these bases. However, the Japanese anticipated that the Allies might still make small-scale attacks against the home islands using naval aircraft flying from aircraft carriers. The government chose not to develop strong defenses to meet the threat of air attack as the country's industrial resources were unable to maintain offensive air forces in China and the Pacific as well as a defensive force in the home islands.
  Few air units or anti-aircraft batteries were stationed in the home islands during the early months of the Pacific War. The General Defense Command (GDC) had been formed in July 1941 to oversee the defense of the home islands, but all combat units in this area were assigned to the four regional military districts (the Northern, Eastern, Central and Western districts) which reported directly to the Ministry of War. As a result, the GDC's functions were limited to coordinating communications between the Imperial General Headquarters—Japan's highest military decision-making body—and the military districts. In early 1942, forces allocated to the defense of Japan comprised 100 Imperial Japanese Army Air Force (IJAAF) and 200 Imperial Japanese Navy (IJN) fighter aircraft, many of which were obsolete, as well as 500 Army-manned and 200 IJN anti-aircraft guns. Most of the IJAAF and IJN formations in the home islands were training units which had only a limited ability to counter Allied attacks. The Army also operated a network of military and civilian observation posts to provide warning of air attack and was in the process of building radar stations. Command and control of the air defenses was fragmented, and the IJAAF and IJN did not coordinate their activities or communicate with each other. As a result, the forces were unable to react to a sudden air attack.
  Japanese cities were highly vulnerable to damage from firebombing due to their design and the weak state of the country's civil defense organization. Urban areas were typically congested, and most buildings were constructed from highly flammable materials such as paper and wood. In addition, industrial and military facilities in urban areas were normally surrounded by densely populated residential buildings. Despite this vulnerability, few cities had full-time professional firefighters and most relied on volunteers. Such firefighting forces that did exist lacked modern equipment and used outdated tactics. Air raid drills had been held in Tokyo and Osaka since 1928, however, and from 1937 local governments were required to provide civilians with manuals that explained how to respond to air attacks. Few air-raid shelters and other air defense facilities for civilians and industry were constructed prior to the Pacific War.
caption: An air-raid shelter being built in Japan, September 1940
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