The Bombing of Cities

Urban bombing existed before the strategic bombing campaigns of 1942–45. Gernika was attacked during an active land campaign in northern Spain. Warsaw was a defended capital under siege in September 1939. Rotterdam was bombed while German ground forces were trying to force a Dutch surrender. Each attack killed civilians and destroyed urban districts, but their immediate military settings differed from the later independent bomber offensives.

A different category emerged when a city or built-up area became a planned instrument of strategic pressure. Japan's raids on Chongqing were sustained after the Chinese government moved inland, with the expectation that bombing could weaken administration, morale and resistance. The German Blitz mixed attacks on docks, factories, railways and communications with pressure on the population. Britain's 1942 area-bombing policy then made the built-up urban area and the morale of industrial workers explicit parts of the targeting system.

Industry, transport, government offices, docks and workers' housing were physically interwoven. Once bomber forces aimed at an urban industrial system, factories and the people living around them occupied the same target space. In 1945 the American incendiary campaign against Japan exploited that overlap directly, while the atomic bombings of Hiroshima and Nagasaki introduced blast, thermal radiation and ionising radiation on a scale that belonged to a different weapons system again.

The early European examples were connected to armies on the ground. Condor Legion records for Gernika sit inside the Northern Campaign of the Spanish Civil War. Warsaw was subjected to air attack and artillery while German forces besieged the capital. Rotterdam was attacked after an ultimatum during the struggle for the Maas bridges and the Dutch defensive system. Civilian terror could contribute to coercion while the operation still remained tied to a land campaign.

By 1942 RAF policy had moved much further. The 14 February directive made enemy civilian morale, particularly that of industrial workers, the primary object of Bomber Command operations; a subsequent clarification identified built-up areas as the general aiming points. Arthur Harris inherited that policy days later and became its most determined operational advocate.

American doctrine formally emphasised daylight precision attack. Over Japan, high-altitude B-29 operations from the Marianas were disrupted by cloud, jet-stream winds, navigation error and mechanical problems. After taking command in January 1945, Curtis LeMay shifted the main urban attack method toward low-altitude night incendiary operations. The transition combined technological constraints with a command decision to use the vulnerability of dense urban-industrial districts to fire.

Atomic bombing introduced another level of decision. The United States used a uranium bomb against Hiroshima on 6 August and a plutonium bomb against Nagasaki on 9 August. These attacks were conducted within the wider campaign to force Japanese surrender, but the weapons produced blast, heat and radiation effects whose scale and persistence differed from conventional incendiary bombing.

Incendiary bombing worked by multiplication. Small magnesium, thermite or gel-fuel bombs were dispersed in large numbers so that firefighters faced many ignition points at once. High explosive could open roofs, rupture water mains, block streets and expose interiors before incendiaries arrived. The destructive system therefore depended on the interaction of bomb types and the number of simultaneous fires.

Navigation determined how tightly that system could be concentrated. German beam systems helped crews find British cities at night; Bomber Command later used Gee, Oboe, H2S and Pathfinder marking; American B-29 formations combined radar and visual methods over Japan. These systems improved the probability of bringing a bomber stream over the intended urban area while accuracy against individual points remained limited in darkness or bad weather.

The city then became part of the weapon equation. Hamburg's dry weather, dense working-class districts and disrupted firefighting contributed to the July 1943 firestorm. Japanese urban construction and dispersed small-scale production made incendiary attack attractive to American planners. Shelters, flak towers, evacuation, firebreaks and firefighting reduced casualties in some circumstances, but no civil-defence system could make a dense city immune to a concentrated fire raid.

The atomic bombs used over Hiroshima and Nagasaki released energy through nuclear fission, producing effects fundamentally different from chemical explosive and incendiary weapons. Blast and thermal effects destroyed large parts of both cities, while prompt and residual radiation produced injuries and deaths that continued after the fires had burned out. This makes the August attacks part of the history of city bombing while requiring a separate account of their weapon effects.

The most reliable way to discuss the human cost is to begin with bounded events. Coventry's 14 November 1940 raid killed 554 people in the current city accounting. Hamburg records about 34,000 to 35,000 deaths during Operation Gomorrah. Dresden's municipal historians' commission concluded that 18,000 to 25,000 people died in the February 1945 attacks. Tokyo's 9–10 March fire raid killed on the order of 100,000 people.

The atomic-bomb figures use a different boundary because radiation-related deaths continued after the day of attack. Hiroshima City estimates that approximately 140,000 people had died by the end of December 1945. Nagasaki's official historical accounting records 73,884 deaths by the end of 1945. Neither figure should be read as the number killed instantly.

National totals are less tidy because studies count different dates, territories and causes of death. Japanese records were disrupted by the destruction itself, while German post-war statistical series changed as new local evidence was incorporated. A range is useful only when the population, period and cause being counted are clear.

Strategic effect differed by campaign. Chiang Kai-shek's government remained in Chongqing and Britain remained in the war through the Blitz. German armaments output could rise while individual cities and industries were devastated because dispersal, substitution and state controls redistributed production. In Japan, urban bombing, blockade, mining, the atomic bombings, military defeat and Soviet entry converged during the final crisis.

The page uses city and national archives first for local destruction and casualties: the Gernika Peace Museum, Rotterdam City Archives, Coventry records, Hamburg's historical collections and the Dresden Historians' Commission. Hiroshima City and Nagasaki City are used for the official end-of-1945 atomic-bomb death estimates.

For policy and operational effect, the British official history, RAF campaign narratives and the United States Strategic Bombing Survey are used alongside wartime command records. The Survey is valuable because it had access to German and Japanese records after the war, but its conclusions remain one body of evidence among production records, city studies and later scholarship.