It's October 1968, and the Soviet Union has just landed astronauts on the moon. Warsaw Pact troops are massing on the Austrian border, and nuclear showdown looms between east and west.
This scenario never happened — except in planning exercises by British civil servants, who meticulously rehearsed how they would govern Britain in the days before, and after, World War III. The details are included in the "War Book," a secret Cold War manual declassified this month for the first time.
The book, which dates from 1970, is a step-by-step guide to dealing with a Cold War crisis, from the first stages of conflict to "R hour" — the release of all Britain's nuclear weapons.
"It's a manual of how to go to war," William Spencer, military history specialist at Britain's National Archives, said Tuesday.
"It's a technical manual in a way, for the people who needed to know," he added. "But it could be seen as a horrific document for some people."
Britain became a nuclear power in 1952, and British politicians were under no illusions about the devastating effects of nuclear war. A 1955 report, kept secret until 2002, estimated that an attack by Soviet hydrogen bombs would kill 12 million people instantly.
So every two years during the Cold War, British civil servants participated in a dry run for the end of the world, practicing how they would do everything from crack down on subversives to evacuate art treasures from London.
The exercises, played out over weeks, included daily mock news briefings from intelligence chiefs describing the unfolding crisis. Senior civil servants played the prime minister and Cabinet, deciding how to respond.
From peace to war
The 1968 exercise, detailed in the newly released manual, imagined Soviet cosmonauts landing on the moon as tensions mounted along the Iron Curtain. Day by day, the crisis escalated: Soviet troops invaded Austria, West Germany, Finland, Turkey, Greece, Italy and eventually "Danish islands." Britons got more and more rattled — first writing letters to newspapers, then staying home from work, stocking up on food and buying supplies to build bomb shelters.
In calm bureaucratic language — loaded with code words to render the book meaningless to those not in the know — the document describes how as the crisis worsened. Civil servants would introduce censorship, evacuate all but the sickest patients from hospitals and eventually be sent to one of 12 underground bunkers scattered around the country.
From these, Britain was to be governed after a nuclear attack, with officials exercising powers of martial law over the remaining population.
Peter Hennessy, a historian who has studied the book, said it provided a glimpse into "one of the darker bits of the British secret state in the Cold War."
"The surprise really is the width and magnitude of it — 16 chapters to get the nation from a peacetime footing to a total war footing. It is a remarkable enterprise," he told the BBC.
"When you consider where this road of decision-taking is leading to, it's the end of the world. There's no other way of looking at it. You would expect it to be cold print, coldly analytical, but this is sheer hell, really, the thought of it."
Retired senior civil servant David Omand said he played the prime minister in one planning exercise and recalled the experience as "quite scary."
"It just gives you a sense of humility that we expect our political leaders to take that kind of responsibility," he told the BBC.
Making contingency plans
The document is the latest in a chilling series of Cold War artifacts that recently have been made public.
In October the National Archives released the scripts of statements the government planned to broadcast on the BBC in the event of nuclear war in the 1970s. "This is the wartime broadcasting service," the announcement began. "This country has been attacked with nuclear weapons."
The government's first "War Book" was created in 1911, and it was updated regularly as warfare and the threats to Britain changed. Its contents were top secret — Spencer said only 96 copies were made of the 1964 book.
It's not known how many copies were made of the 1970 version. Parts of it were published in 2000, but the whole book was only released by the National Archives this month. Later versions remain classified.
The government no longer plans for war with the Soviet Union, which collapsed in 1991, but it still keeps a "War Book" and rehearses for disasters such as a major terrorist attack.
A Cabinet Office spokesman would give no details of the current plans, saying only that there are "lots of contingency plans to deal with lots of different crises we face today."