Square Leg
Square Leg was a British government home defence Command Post and field exercise which was held from 11 to 25 September 1980 and 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; the exercise scenario of 150 nuclear weapons striking Britain, with the majority of these weapons having a yield ranging from 500 kilotons to 3 megatons and a resulting total yield of 280.5 megatons, was felt to be reasonably realistic, but the post-exercise report stated that a total strike in excess of 1,000 megatons would be more likely.