Square Leg

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'Square Leg' target plot
Square leg is also a fielding position in cricket; see Fielding (cricket).

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 MoD and Government. Part of the exercise involved a mock nuclear attack on the British Isles. 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] This was felt to be a reasonably realistic scenario, although the report stated that a total strike in excess of 1,000 megatons would not be unexpected.

Mortality was estimated at 29 million (53% of the population); serious injuries at 7 million (12%); short-term survivors at 19 million (35%).

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—whereas 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; no targets in Inner London are attacked (for example Whitehall, the centre of British government); towns such as Eastbourne are hit for no obvious reason.[2]

Operation Square Leg was one of the exercises used to estimate the destructiveness of a Soviet nuclear attack in the 1984 BBC production Threads.

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  1. ^ Doomsday, Britain after Nuclear Attack, p. 102
  2. ^ Doomsday, Britain after Nuclear Attack, p. 105