Air raids on Japan

• 1. Introduction

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  Air raids on Japan transformed the Pacific War into a campaign fought over cities, factories, and the lives of millions of civilians. Between 1942 and 1945, Allied forces struck the Japanese home islands with a scale and ferocity that left few major urban centers standing. The most commonly cited estimate puts Japanese casualties at 333,000 killed and 473,000 wounded, though other tallies of total fatalities range as high as 900,000. The largest single raid of the entire Second World War came on the 1st of August 1945, when 836 B-29s dropped more than six million tons of bombs and mines in a single operation. How did a campaign that began with sixteen borrowed medium bombers in 1942 grow into that? And what decisions, failures, and moral turning points shaped the path from the first tentative attack to the atomic bombs over Hiroshima and Nagasaki? Those questions run through every phase of the story.

• 2. Plans Before the First Bomb

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  In 1940, the United States Army Air Corps began drawing up contingency plans for bombing Japan, more than a year before the two countries were at war. The same year, a naval attache reporting from Tokyo described Japan’s civil defenses as weak. American planners sketched out raids from Wake Island, Guam, the Philippines, and the Chinese coast, but Japanese forces swept those bases away in late 1941 and early 1942. When Japanese aircraft attacked Clark Air Base on the 8th of December 1941, the USAAF heavy bomber force in the Philippines was largely destroyed on the ground.

  On the Japanese side, prewar strategists judged Soviet aircraft based in the Russian Far East to be the greater threat, not American bombers crossing the Pacific. Japan’s government made a deliberate choice not to build strong domestic air defenses, because its industrial resources were already stretched maintaining offensive air forces in China and across the Pacific. In early 1942, the entire fighter force assigned to defend the home islands numbered around 100 Imperial Japanese Army Air Force aircraft and 200 Imperial Japanese Navy fighters, many of them obsolete. Anti-aircraft coverage was equally thin, with roughly 500 army guns and 200 navy guns protecting a nation of densely packed, largely wooden cities.

  That density mattered. Urban areas were typically congested, with most buildings made from paper and wood. Air raid drills had been held in Tokyo and Osaka since 1928, and from 1937 local governments were required to give civilians manuals on responding to attacks, but few actual shelters were ever built. The inadequacy of those preparations would prove catastrophic within a few years.

• 3. The Doolittle Raid

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  On the 18th of April 1942, sixteen B-25 Mitchell medium bombers launched from an aircraft carrier that had transported them from San Francisco to within striking range of Japan. Each aircraft flew independently to bomb targets in Tokyo, Yokohama, Yokosuka, Nagoya, and Kobe. Local air defense units were caught completely off guard, and all sixteen B-25s escaped without serious damage. Japanese casualties were 50 killed and over 400 wounded; about 200 houses were destroyed. The physical damage was minimal.

  The ripple effects were anything but. The Japanese military leadership was badly embarrassed, and four fighter groups were pulled from the Pacific theater to bolster the home islands’ defenses. The Imperial Japanese Navy, in part to prevent further naval air raids, launched an offensive in the Pacific that ended in the decisive defeat at the Battle of Midway. The Imperial Japanese Army drove into central China to capture the airfields at which the Doolittle Raiders had intended to land, an offensive that resulted in the deaths of 250,000 Chinese soldiers and civilians. The Japanese Army also began developing fire balloons capable of carrying incendiary and anti-personnel bombs from Japan all the way to the continental United States, a project that would not bear meaningful results.

  For the Americans, Lieutenant Colonel James H. Doolittle became an instant war hero. The raid demonstrated that Tokyo was within reach. The question was how to reach it again, in larger numbers, and with a platform capable of doing real damage.

• 4. Operation Matterhorn’s Failures

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  The Boeing B-29 Superfortress was the aircraft the USAAF had been waiting for, a bomber with the range to strike Japan from bases far enough away to be defensible. In late 1943, the Joint Chiefs of Staff approved Operation Matterhorn, a plan to base B-29s in India and fly them forward through staging fields near Chengdu in China to reach targets in Japan. The construction of those Chinese airfields required around 300,000 conscripted laborers and 75,000 contracted workers. The Twentieth Air Force was formed in April 1944 specifically to manage B-29 operations, with General Henry H. Arnold taking its personal command from the Pentagon, an unprecedented arrangement.

  The first raid from the China bases took place on the night of 15 and the 16th of June 1944, when 75 B-29s were sent to attack the Imperial Iron and Steel Works at Yawata in northern Kyushu. The attack caused little damage and cost seven B-29s. When the Yawata commander, Brigadier General Kenneth Wolfe, could not mount follow-up attacks because of inadequate fuel stockpiles in China, Arnold relieved him. His replacement was Major General Curtis LeMay, who had commanded Eighth Air Force bombing attacks against Germany.

  Operation Matterhorn ultimately flew nine raids against Japan from its China bases, succeeding only in destroying a single aircraft factory at Omura. XX Bomber Command lost 125 B-29s during all of its India-and-China operations, but only 22 to 29 were destroyed by the Japanese; the rest were lost to flying accidents. The official USAAF history concluded that the difficulty of supplying adequate fuel and bombs across the Himalayas was the chief reason the campaign failed. Adverse weather over Japan, technical problems with the aircraft, and inexperienced crews compounded the difficulties.

• 5. From Precision to Fire

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  When airfields in the Mariana Islands became available following the capture of Guam, Saipan, and Tinian between June and August 1944, XXI Bomber Command shifted its operations there. These islands sat 1,500 miles south of Tokyo and could be resupplied by sea, making them far better bases than the China fields had ever been. By the time 1944 was ending, hundreds of B-29s were arriving.

  XXI Bomber Command’s early strategy centered on high-altitude daylight precision bombing of Japanese aircraft factories. The first attack, Operation San Antonio I, sent 111 B-29s against the Musashino aircraft plant outside Tokyo on the 24th of November 1944. Only 24 reached the primary target. High winds over Japan and persistent cloud cover frustrated raid after raid. Brigadier General Haywood Hansell, who commanded XXI Bomber Command, believed precision bombing was slowly producing results, but Arnold disagreed and in late December 1944 decided to replace him with LeMay.

  LeMay ordered a fundamental change in tactics. Beginning in early March 1945, B-29s would fly at the low altitude of 5,000 feet, at night, armed with incendiary bombs, with most defensive guns removed to allow them to carry more ordnance. Japan’s night fighter force was weak, and the anti-aircraft batteries were far less effective in darkness. Planners had been studying the feasibility of firebombing since 1943, testing incendiary bombs on Japanese-style buildings at Eglin Field and at a purpose-built “Japanese Village” at Dugway Proving Ground. Napalm production had grown from 500,000 pounds in 1943 to eight million pounds in 1944, and large stocks of M-69 incendiary cluster bombs had been stockpiled across the Pacific. LeMay did not seek Arnold’s specific approval before beginning his firebombing campaign, to shield Arnold from blame if the attacks failed.

• 6. Operation Meetinghouse and the March Campaign

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  On the afternoon of the 9th of March 1945, 346 B-29s departed the Marianas for Tokyo. They began arriving over the city at 2:00 am Guam time on the 10th of March, and 279 bombers dropped 1,665 tons of bombs. The resulting conflagration overwhelmed Tokyo’s civil defenses and destroyed 16 square miles of buildings, representing seven percent of the city’s total area. The Tokyo police and fire department estimated 83,793 people killed, 40,918 injured, and just over one million left homeless. Postwar estimates of deaths ranged from 80,000 to 100,000. Only fourteen B-29s were lost to combat or mechanical failure. Operation Meetinghouse was the single most destructive air raid of the war.

  XXI Bomber Command pressed on immediately. On the 11th of March, 310 B-29s attacked Nagoya, burning out 2.05 square miles; no B-29s were lost. On the nights of 13 and the 14th of March, 274 Superfortresses hit Osaka and destroyed 8.1 square miles. Kobe followed on the night of 16 and the 17th of March, when 331 B-29s created a firestorm that destroyed half the city’s area, killed 8,000 people, and left 650,000 homeless. Nagoya was struck again on 18 and the 19th of March, with 2.95 square miles destroyed. The first firebombing campaign then paused: XXI Bomber Command had exhausted its supply of incendiary bombs.

  American losses in these five raids were strikingly low relative to the destruction inflicted, and the USAAF assessed the campaign a success. The Japanese government ordered the evacuation of all schoolchildren in the third through sixth grades from the main cities; by early April, 87 percent of them had left. The Japanese military’s inability to stop the raids was becoming obvious to ordinary citizens.

• 7. The Empire Plan and Smaller Cities

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  By June 1945, the six largest Japanese cities had been largely destroyed. Across the Tokyo, Osaka, Nagoya, Yokohama, Kobe, and Kawasaki attacks, over 126,762 people had been killed and one and a half million dwellings destroyed; the area leveled in those three cities alone exceeded the total area destroyed in all German cities by both American and British forces combined. With the major targets gone, Arnold visited LeMay’s headquarters at Saipan in mid-June and approved a new plan targeting twenty-five smaller cities with populations ranging from 62,280 to 323,000.

  On the first night of the small-city campaign, the 17th of June, four cities were each attacked by a wing of B-29s. Hamamatsu, Kagoshima, and Yokkaichi suffered extensive damage. The cities were almost undefended, and no B-29s were lost. That pattern continued through the summer: on most raid nights, four cities were attacked, each by a single wing. Sixteen multi-city incendiary attacks had been completed by the end of the war, targeting 58 cities. Because the small cities lacked anti-aircraft guns and Japan’s night fighters had become largely ineffective, only a single B-29 was shot down during the entire small-city campaign.

  Alongside the firebombing, B-29s were distributing propaganda on a massive scale. Estimates put the total at 10 million leaflets dropped in May, 20 million in June, and 30 million in July. On the night of 27 and the 28th of July, six B-29s specifically warned eleven named cities that they would be attacked, with six of those cities struck the following night. On the 1st of August, the campaign reached its peak: 836 B-29s mounted the largest single raid of the entire war, devastating Hachioji, Mito, Nagaoka, and Toyama; 99.5 percent of buildings in Toyama were destroyed.

  Separately, the 315th Bombardment Wing conducted a night precision campaign against Japan’s oil industry using the advanced AN/APQ-7 radar. But as Japan had almost no crude oil to refine because of the Allied naval blockade, those raids had little effect on the country’s ability to fight.

• 8. Mining, Naval Attacks, and the Path to Surrender

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  LeMay’s aerial mining campaign, designated Operation Starvation, ran alongside the bombing and proved quietly devastating. The 313th Bombardment Wing laid its first mines in the Shimonoseki Strait on the night of 27 and the 28th of March 1945 to block Japanese warships from attacking the Okinawa landing force. By the end of the war, Superfortresses had sunk 293 ships through mines alone, accounting for 9.3 percent of all Japanese merchant shipping lost during the Pacific War and 60 percent of losses between April and August 1945. Many of Japan’s major harbors, including Tokyo, Yokohama, and Nagoya, were closed to shipping entirely. The 313th Bombardment Wing lost only 16 B-29s in these operations.

  The United States Navy contributed its own attacks on the home islands. Task Force 58, comprising eleven fleet carriers and five light carriers, struck airfields and aircraft factories in the Tokyo region on 16 and the 17th of February 1945. American naval aviators claimed 341 aircraft kills and the destruction of another 160 on the ground, against the loss of 60 aircraft in combat and 28 in accidents.

  By June 1945, the Japanese military had decided to stop contesting most Allied air raids, conserving what aircraft remained for defense against the anticipated Allied invasion of the home islands. The Allied bombing campaign was assessed by historians and American planners as one of the main factors that led the Japanese government to surrender in mid-August 1945. The morality of the large-scale city attacks, and especially the decision to use atomic bombs against Hiroshima on the 6th of August and Nagasaki on the 9th of August, has remained among the most contested questions in the history of the war. Following the conflict, the United States Strategic Bombing Survey concluded that the Twentieth Air Force should have placed greater emphasis on attacking Japanese shipping, given how effective Operation Starvation had turned out to be.