Estimated Impact of a Hiroshima-scale Nuclear Explosion in LONDON: Classified official schematics depict devastation if a nuclear weapon had been detonated in the UK during 1945
In the final years of World War II, the British government, under the leadership of Clement Attlee, contemplated the potential catastrophic effects of an atomic bomb detonation over London. The British Mission to Japan, in their report titled 'An Investigation of the Effects of the Atomic Bombs Dropped at Hiroshima and Nagasaki', outlined the projected devastation.
The key for the second map, compiled by the British Mission, explains the colours detailing the respective levels of destruction. The official report emphasised that a single atomic bomb detonation would cause complete destruction of a large urban area, with catastrophic damage to industrial and military targets, the collapse of surrounding buildings, and massive civilian casualties.
The envisioned effects mirrored the U.S. targeting criteria used for Hiroshima, which was chosen for its industrial-military importance, urban density, and surrounding hills to contain the blast. The British projections expected near-total demolition of buildings within several square miles, intense fires and blast waves destroying infrastructure, and high fatalities and casualties mainly among the civilian population.
While no direct British government document from 1945-1946 in the search results explicitly details London's projected atomic effects, the U.S. Target Committee Minutes and allied strategic bombing criteria aimed for a large enough blast for complete urban destruction, targeting industrial and military centers untouched by earlier bombing, and preference for geographic features that would corral the shockwave.
Official diagrams envisaged the impact of atomic bomb blasts in London, with the force described as being equivalent to what was unleashed on Hiroshima and Nagasaki. The first map imagined the impact of a bomb detonated over Trafalgar Square, with everything within 1,000 yards of the epicenter being totally wiped out. The second map, found at the National Archives, imagines five separate atomic bomb blasts in London.
Areas such as Buckingham Palace, the BBC's headquarters, and the British Museum would have faced damage 'beyond repair' within a distance of one mile. The report estimated that around 400,000 people might be temporarily homeless due to the blast. The police, fire, and ambulance services were all virtually wiped out, with survivors left to fend for themselves before help arrived from further afield.
In Hiroshima, the blast obliterated everything within the surrounding square mile, killing around 80,000 people in the blink of an eye. St Paul's Cathedral, Smithfield Market, Victoria Station, and Marble Arch were within the third ring up to 1.5 miles away, described as 'uninhabitable without major repairs'. The final ring - up to 2.5 miles away - includes King's Cross Station, the Bank of England, Tower Bridge, Battersea Power Station, and Regent's Park.
Areas such as Lambeth in the south of the capital would have been unscathed, but the borough's inhabitants would have faced having to grapple with a likely total breakdown in law and order and a collapse of the emergency services. The attack on Nagasaki occurred on August 9, 1945, and the device used, named Fat Man, claimed at least 50,000 more lives and wiped out a third of the city. At least 30,000 more died from their devastating injuries in the 48 hours that followed.
The 'Protect and Survive' public information campaign was released in the 1970s, advising Britons to prepare a fall-out room and store supplies for two weeks. The maps were part of a file that also includes the report titled, 'An Investigation of the Effects of the Atomic Bombs Dropped at Hiroshima and Nagasaki'. The British perspective in that era, in line with contemporary American planning, saw atomic detonations over major cities like London as weapons of unparalleled destruction, inflicting overwhelming damage to both civilian and military assets to hasten war termination. This mirrored U.S. estimates around Hiroshima, which predicted about 100,000 fatalities and nearly total destruction of target areas.
Despite the British government's report focusing on Hiroshima and Nagasaki, it is evident that they anticipated the devastating impact of an atomic bomb on urban areas, specifically London, given the similarities in target criteria and expected effects. The British projections foretold decimation of civilian populations, collapse of infrastructure, and widespread destruction, similar to the aftermath of 'war-and-conflicts' bombings during World War II.
The 'Protect and Survive' campaign, unveiled in the 1970s, underlined the need for preparedness for potential atomic bomb detonations in major cities, underlining the threat that such weapons posed to civilian populations in general-news stories, particularly within the context of politics and policy-and-legislation.
