- 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 Ministry of Defence 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) with yields of 500kt to 3mt  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 percent of the population); serious injuries at 7 million (12 percent); 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—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.
- Nuclear weapons and the United Kingdom
- World War III
- The Warsaw Pact operation Seven Days to the River Rhine
- RAF Greenham Common airfield
- Doomsday, Britain after Nuclear Attack, Stan Openshaw, Philip Steadman and Owen Greene, Basil Blackwell, 1983 ISBN 0-631-13394-1
- War Plan UK, Duncan Campbell, ISBN 0-09-150671-9
- The National Archives, FCO 46/2446, 2447, 2448
- Doomsday, Britain after Nuclear Attack, p. 102
- Doomsday, Britain after Nuclear Attack, p. 105