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. While featuring some conventional warfare elements such as troop mobilisation, much 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. An increased ratio of ground bursts to air bursts was depicted to provide all the regional NBC cells with radioactive fallout challenges,The National Archives, HO 322/950 with underwater bursts also being depicted. 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.
Partial bomb plots were released for England and Wales and for Scotland, but not for Northern Ireland. In the immediate absence of official casualty estimates, Stan Openshaw and Philip Steadman produced an independent estimate of 29 million deaths (53 percent of the population) and 7 million seriously injured (12 percent), with uninjured short-term survivors numbering 19 million (35 percent). By 1982, an official estimate was available which gave the following numbers; 8.5 million blast wave deaths, 2.5 million radiation deaths, 2 million severely injured, and 41 million uninjured.
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 Mt 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 meant that much of the Inner London area was still destroyed; towns such as Eastbourne were hit for no obvious reason.Doomsday, Britain after Nuclear Attack (1983), Stan Openshaw, Philip Steadman and Owen Greene, Basil Blackwell, p. 105 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. 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.
The British military's involvement with Square Leg fell under the auspices of the wider "Crusader 80" series of exercises.
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, but otherwise, despite providing a "major boost" to the nuclear disarmament movement, it was not met with significant opposition in the way that the later Hard Rock exercise would be.
Timeline of main events and civil and armed forces actions
Transition to War The following table shows the hypothetical pre-strike event list drawn from the national Main Event List for Square Leg, testing the Transition to War stage. +Date Event January 1980Warsaw Pact, which has recently come under new leadership, holds military exercises similar to those usually held in the summer. While Pact forces would normally return to base after end of exercise, on this occasion they remain close to NATO's frontier.April - August 1980Soviet Union demands that Norway and Denmark withdraw from NATO, sparking diplomatic tension that continues into August. Public reaction is calm as the situation is believed to be just another deterioration in East-West relations.By early August 1980NATO commanders declare a state of vigilance in anticipation of war. Reserve forces are mobilised and civil defence planning is initiated at a covert level. "A very few senior key personnel" man SRHQs while County and District authorities begin attack preparations.
UKWMO is briefed and begins its own preparations.
Planning is not publicly admitted to at this stage in order to avoid public alarm and in order not to precipitate an attack (it is still hoped that a diplomatic solution can be reached).Prior to and including 15 AugustPlanning becomes more overt in the continued absence of a diplomatic solution. Major urban centres clear their hospitals of patients and all but a few staff members in order to make way for anticipated casualties, prompting protests from patients and their families, and from local authorities who find themselves facing increased pressure on care home places. Cabinet instructs all departments and specified authorities to review their plans for Transition to War. SRHQs and local authority emergency centres are fully prepared.16 AugustFuel rationing imposed, leading to queues at petrol stations and police needing to be drafted in to prevent hoarding.27 AugustGovernment requests preparations to be made to remove art treasures.31 AugustIndustrial unrest and large-scale activity by extreme left- and right-wing parties. Resentment is directed at the heavier than usual police presence and the police's role in controlling subversives and potential subversives. Multiple arrests made under emergency powers. Arson attacks on industrial sites, supermarkets, etc. Police require military assistance to quell some of the unrest; they manage to do so without shots being fired.1 SeptemberConsiderable cross-Channel movement into the UK by expatriate families on a self-evacuation basis.7 SeptemberPrime Minister addresses nation via TV and radio.9 SeptemberSecretary of State authorises power of direction over British Airways and national shipping.11 SeptemberPrime Minister again addresses nation.12 SeptemberProtect and Survive instructions, which were already available at libraries and HMSO in pamphlet form, are issued through the media. Those who intend to follow instructions begin doing so. Cabinet approves Queen's Order 2, effectively dissolving Parliament and granting emergency powers to the government.
Directed food buying (by government departments, police, and military services, etc.), accompanied by panic buying breaking out in some areas and subsequent price rises.
Noticeable rundown of industry. Key points placed under guard. Essential Service Routes designated and closed off to the general public; few local authorities have dedicated plans, with others either repurposing existing plans or acting in a completely improvised manner. Between ten and thirty per cent of persons in perceived target areas ignore advice to stay at home and instead self-evacuate, causing further difficulties for local authorities who are under no obligation to assist such evacuees (though some do).
Local authorities, MPs, police, and the services swamped with offers of help in forming some sort of civil defence/Home Guard organisation. Local authority attitudes vary; many turn down offers of civilian help despite government encouragement to use such help, while some others take on civilians with relevant skills in order to make up for staff desertions.13 September Prime Minister speaks to nation for a third time. Panic food buying continues.15 SeptemberGeneral Alert and war declared. Fighting breaks out on continent. Conventional bombing on defence related targets in UK. Public reaction to bombing is mixed - those living in high-rise flats and in areas generally thought to be obvious targets leave home quickly. Industry seriously affected. Schools close in afternoon.17 SeptemberFighting on continent escalates. Government authorises local authorities to staff their wartime headquarters.
Public passenger transport operating at fifty per cent of capacity.
Government orders manning of headquarters in the Regions.19 SeptemberSatellites and RAF Fylingdales detect incoming nuclear attack. Attack Warning Red 11.55 am. Nuclear strike starts at 12.01 pm and ends at 12.10 pm. Strike mainly hits military and communications targets, though civilian areas are also targeted. Loss of RAF Fylingdales and other communication difficulties caused by the first strike mean that no warning can be provided when a second strike begins. This strike starts at 13.00 and sporadically "drift[s] in" until 15.00, and targets population centres and industrial sites along with some repeat strikes on first wave targets.
Survival The following table of Square Leg's 'survival' period, detailing the events that occurred in the first two weeks following the attack, is extracted from the Warwickshire County War Diary. +DateEvent20 SeptemberDaily food requirements - 680,700 rations. Eighteen thousand people (in refugee camps) suffering third-degree burns. Isolated reports of refugees leaving West Midlands area. 22 SeptemberCasualty aid points swamped. Hospitals and improvised hospitals full. Decision taken to conserve police strength with a view to deployment of Police Support Units later.23 SeptemberCommence mass advice to achieve public order. Reappraise triage. Request medical aid from military.24 SeptemberEstablish additional casualty aid points close to existing where possible. Commit to home nursing casualties who will probably die. Commence grave-digging operations. (Transport) Remove dead from casualty aid points; remove dead from damaged areas as radiation levels permit. Fire situation in county under control.25 SeptemberIdentify rationing levels of food and water. Identify additional rationing requirements of workers. Flow of refugees from the West Midlands is indicated; 31,000 to North Warwickshire, 12,000 to South Warwickshire.27 SeptemberCasualty figures Rugby area is indicated 30,000 plus estimate, Nuneaton area 17,000 plus. Large numbers of persons suffering first stages of radiation sickness. Arrange for establishment of decontamination units. Consider variations to law - liaise with police. 28 SeptemberEstimate 100,000 plus refugees coming from West Midlands - most injured/shocked/irradiated. Consider disinfection in Rugby/Coventry area to avert disease. Liaise with military for aircraft for spraying. Control of refugees in the west of the county impossible at this date.