America emerged from World War II as the most powerful nation on earth. Not only did it produce half of the world’s economic output, but it was also in sole possession of the most devastating weapon ever created. Initially, U.S. officials believed America’s nuclear monopoly would endure for some time. After the war, Gen. Leslie Groves, the brilliant manager of the Manhattan Project, predicted the Soviet Union would not explode its first atomic bomb for two decades.

The United States was therefore shaken when the Soviet Union entered the nuclear club on August 29, 1949. As harrowing as this experience was, it was quickly overshadowed by the prospect of Moscow acquiring thermonuclear weapons and the means to deliver them to the U.S. homeland.

The implications of this was brought into sharp relief on March 1, 1954, when the United States conducted its first test of a deliverable hydrogen bomb. Known as Castle Bravo, the scientists badly misjudged the yield of the bomb, which was about fifteen megatons compared to the five or six megatons they were predicting. The resulting radioactive fallout went far beyond what the test team was expecting, nearly killing the testing team in the process. The test did contaminate nearby islanders as well as the unlucky inhabitants of a Japanese fishing boat, Lucky Dragon, that happened to be in the area at the time of the test. All of the crew became sick, and one person died shortly after returning to Japan.

After the test, President Dwight D. Eisenhower’s science advisers superimposed the fallout patterns of the Castle Bravo test on a map with Washington, DC as ground zero. The results were shocking. As Annie Jacobsen recounts in her fantastic book on the history of DARPA:

If ground zero had been Washington, D.C…. every resident of the greater Washington-Baltimore area would now be dead. Without a Station 70–style bunker for protection, the entire population living there would have been killed by 5,000 roentgens of radiation exposure in mere minutes. Even in Philadelphia, 150 miles away, the majority of inhabitants would have been exposed to radiation levels that would have killed them within the hour. In New York City, 225 miles north, half of the population would have died by nightfall. All the way to the Canadian border, inhabitants would have been exposed to 100 roentgens or more, their suffering similar to what the fisherman on the Lucky Dragon had endured.

The prospect of the Soviet Union being able to wreak this kind of devastation on America not only terrified U.S. officials, but also created an enormous quandary for strategy. After all, America’s strategy was to use nuclear weapons to offset the Soviet Union’s quantitative advantages in Europe. This strategy was plausible when Moscow couldn’t retaliate against the U.S. homeland, and possibly if it could only do so with a limited number of atomic weapons, but how could it be in an age of thermonuclear weapons that destroyed entire cities?

Civil defense was one idea to make the strategy work. The thinking was that if the United States could limit the damage the Soviet Union could do to the homeland, the threat to use nuclear weapons in Europe would be more credible. In the popular imagination, civil defense has become synonymous with the duck and cover drills in American schools. In reality, the plans were much more elaborate—though not any less insane.

Throughout the 1950s and into the 1960s, the U.S. government vacillated between plans that called for evacuating cities and ones that centered around building fallout shelters to allow urban areas to ride out the attacks. The responsibilities and roles of the federal, state, and local governments were also constantly in flux, and how much money to devote to these efforts was frequently debated.

The federal government went to considerable lengths during the Eisenhower administration to make these civil defense plans seem plausible, even if the president himself doubted their efficacy. For example, starting in 1954 the United States began holding annual nation-wide exercises called “Operation Alert,” that practiced how to respond to Soviet nuclear attacks on American cities. The results were not encouraging.

Congress also tried to enhance Americans’ confidence in their ability to survive a nuclear war. Most notably, in 1956 it began holding a series of hearings called the Holifield Committee, named after the Democratic Congress member, Chet Holifield, who was an especially strong proponent of civil defense. The hearings were nothing if not exhaustive. As one historian tells it,“The 1956 Holifield hearings lasted six months and included 211 witnesses, whose testimony filled 3,145 pages. They comprised the most thorough investigation of civil defense ever undertaken.”

If the purpose of the hearings was to bolster public confidence in civil defense, they were a spectacular failure. Indeed, the hearings demonstrated quite clearly how outrageous these efforts were. The most devastating testimony came from Frederick “Val” Peterson, a former governor of Nebraska, who Eisenhower appointed as director of the Civil Defense Administration. As Annie Jacobsen recounts, during the hearings Peterson

revealed that the plan of the administration was to dig roadside trenches along public highways leading out of all the big cities across the nation. The trenches were to be three feet deep and two feet wide. When the bombs hit the cities, Peterson said, people who had already made it out were to stop driving, abandon their automobiles, lie down in the trenches, and cover themselves with dirt.

Naturally, this prompted a senator to ask how the government intended to provide basic services, such as food, water and sanitation, to the people in these trenches. Peterson admitted that “Obviously, in these trenches, if they are built on an emergency basis,” they would not have these things. In fact, the entire food situation would be quite grim. “I think the best we will be able to do in the United States is to run soup kitchens,” Peterson said. “We can't eat canned foods, we won't eat refrigerated foods. We will eat gruel made of wheat cooked as it comes out of the fields and corn parched and animals slaughtered as we catch them before radioactivity destroys them.” Summoning his inner Hobbes, Peterson declared, “If this kind of war occurs life is going to be stark, elemental, brutal, filthy and miserable.” In other words, the survivors would likely envy the dead.

The civil defense efforts were not completely for naught, however. For instance, the need to evacuate cities was one of the rationales for building the federal interstate highway system. Civil defense planning also forced the government to consider how to ensure continuity of government following an attack. This led Washington to build elaborate shelters for the president and other parts of the executive branch, members of Congress, the Supreme Court, as well as take other steps to beef up command and control measures. All of these measures were necessary to enhance the credibility of America’s strategic deterrent, which ultimately prevented the civil defense plans from being needed at all.

Zachary Keck is the former managing editor of The National Interest. You can find him on Twitter: @ZacharyKeck.

Image: One of two U.S. Air Force B-1B Lancer bomber is seen from a refueling aircraft during a mission to fly in the vicinity of Kyushu, Japan, the East China Sea, and the Korean peninsula June 20, 2017. U.S. Air Force/Airman 1st Class Gerald R. Willis/Handout via REUTERS.