If you read between the lines in the document, it is obvious that the government EXPECTED heavy casualties from an attack, no matter what was done. But the plan was to get people out of the cities because the concentration makes a fine target and because a hit or near miss creates many casualties. The joke that almost only counts in horseshoes, grenades and nuclear warfare lost its luster. The Interstate highway system (incidentally called the Eisenhower System) was started about in the middle 50's, about the time this document was printed. The thrusts of the interstate highway system was to allow large amounts of troops and supplies to move within the country and to allow us to evacuate the cities if we had a couple of hours before an attack.
Anyone who has tried to get out of a major city at rush hour knows the futility of this plan. In addition, the decision to put the population on the road placed them in great jeopardy because an automobile affords little protection. Although some would die in the city, if they were only partly out of the city and in automobiles the death toll could be higher. I think we can use a corollary here, it is generally better to be in a permanent structure than a motor vehicle in a storm.
Many of the futile attempts at atomic security look funny now. But let's put this into a different perspective. The USSR had several thousand bombs, many in the 50 to 100 Megaton range, compared to the 20 Kiloton range for the Hiroshima and Nagasaki bombs. They could target the area surrounding the city as well as the center. A 20KT bomb has a near 100% kill zone of about 1 mile radius. Of course a 20MT does not have a kill area of 1000 times that distance. In fact the 100% kill zone is only somewhere about a 15 mile radius. The word "only" is interesting.
To create "Case Headless', the government plan for handling an attempt by the Soviet Union to "decapitate" the US by killing the government one 100MT bomb targeted for the center of Washington DC could miss by about fifteen miles and be a success. By comparison a 20 KT bomb like Hiroshima would have to hit within about one half mile of its target to achieve success.
As already stated, a characteristic feature of the atomic bomb which is quite foreign to ordinary explosives is that a very appreciable fraction of the energy liberated is turned into radiant heat and light. With TNT or Plastic explosive the largest component is the blast, heat and flash are there but are small components. Before the first atomic explosions we had no idea what the effect would be. For a sufficiently large explosion the flash burns produced by this radiated energy will become the dominant cause of damage, since the area of burn damage will increase roughly in proportion to the energy released, whereas the area of blast damage increases only with the two-thirds power of the energy.
Although the mechanism of damage was more evenly balanced at 20 KT the size of the Hiroshima and Nagasaki bombs, the effects of the flash were, however, very evident, and many casualties resulted from flash burns. A discussion of the casualties caused by flash burns will be given later; in this section will be described the other flash effects which were observed in the two cities.
This information is from THE ATOMIC BOMBINGS OF HIROSHIMA AND NAGASAKI by The Manhattan Engineer District, June 29, 1946 which can be located on the web.
The thrust of this whole HPE document is simple, have enough of our society survive to continue it. We apparently concede that there will be losses and they will be substantial. We have a corollary today with the declining of the ABM. In the 80's we felt a system to ward off the thousands of USSR warheads was totally impractical. We would have had to knock out nearly one hundred percent of the warheads to avoid a disaster, something considered impractical.
If five percent of the USSR's arsenal got through, or put another way, if we only knocked down ninety five percent it was unacceptable. We signed a treaty with the Soviet Union to not pursue ABM and worked to reduce the chance of a launch. But the situation has changed. A system that will knock out a few warheads, even if multiple targeting of the warheads is needed is a viable system now. A launch by the USSR is very unlikely. But the third world countries that are now joining the nuclear club have only a few warheads and a few launch vehicles.
Let's say we build 2000 ABM missiles. The Soviets could have overpowered them by launching more than 1500 vehicles, assuming some of the ABM units miss. Even a five percent miss rate would have let a hundred of them through. But if we had an attack with 10 missiles, five percent of the 2000 could be fired to target each missile with 10 ABM's making a hundred percent kill of the weapons likely. No matter how good or bad the system has a better chance of success.
