Square Leg was a 1980 British government home defence Command Post and field exercise, which tested the Transition to War and Home Defence roles of the Ministry of Defence and British government. Part of the exercise involved a mock nuclear attack on Britain. It was assumed that 131 nuclear weapons would fall on Britain with a total yield of 205 megatons (69 ground burst; 62 air burst)[1] with yields of 500 KT to 3 MT.[2] That was felt to be a reasonably realistic scenario, but the report stated that a total strike in excess of 1,000 megatons would be likely. The ratio of ground bursts to air bursts was increased to provide all the regional NBC cells with radioactive fallout challenges.[3] Furthermore, the scenario was altered from official assessments as these were highly classified and many participants did not have the appropriate clearance to see them.[3]
Mortality was estimated at 29 million (53 percent of the population), serious injuries at 7 million (12 percent), and short-term survivors at 19 million (35 percent).
Square Leg was criticised for a number of reasons: the weapons used were exclusively in the high-yield megaton range, with an average of 1.5 megatons per bomb, but a realistic attack based on known Soviet capabilities would have seen mixed weapons yields, including many missile-based warheads in the low-hundred-kiloton range. Also, no targets in Inner London were attacked (for example, Whitehall, the centre of British government), though collateral damage from strikes on Outer London targets and on Potters Bar and Ongar[nb 1] meant that much of the Inner London area was still destroyed;[4] towns such as Eastbourne were hit for no obvious reason.[nb 2][5] All government and military bunkers were assumed to have survived for exercise purposes, although Kelvedon Hatch Sub-Regional Headquarters had difficulty in establishing regional control.[3] The United Kingdom Warning and Monitoring Organisation was not a "live" participant, with the strike data it would have provided instead being pre-recorded and played into the exercise as it proceeded, an aspect that was criticised by participants after the exercise.[3]
The Lothian Regional Council refused to participate in Square Leg, and the exercise came under journalistic scrutiny after its details were leaked to the press,[6] but otherwise it was not met with significant opposition in the way that the later Hard Rock exercise would be.
- ^ Doomsday, Britain after Nuclear Attack, p. 102
- ^ "UK | Fallout Warning". falloutwarning.wordpress.com. Archived from the original on 3 January 2014. Retrieved 12 January 2022.
- ^ a b c d The National Archives, HO 322/950
- ^ a b Campbell, Duncan (3 October 1980). "World War III: an exclusive preview" (PDF). New Statesman. Retrieved 6 July 2024 – via duncancampbell.org.
- ^ Doomsday, Britain after Nuclear Attack, p. 105
- ^ Campbell, Duncan; Edwards, Rob (3 October 1980). "Square Leg caught out" (PDF). New Statesman. Retrieved 6 July 2024 – via duncancampbell.org.
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