YOU’LL HAVE SEEN the photos of the Japanese cities of Hiroshima and Nagasaki after the American atomic bombs hit them in August 1945. Those black-and-white pictures of what looks like an archaeological dig: the husks and shadowy traces of an ancient civilization revealed by scraping the surface of the earth away. The grid of streets traced in pale ash. Here and there, rectangular shadows that might have been houses, office blocks. Black holes, pits, that once had a purpose, once had been part of something. Scorched wisps of what look like hair but are congealed tangles of steel. Of human beings, those frail things, there is no sign or remnant.

Strangely, Hiroshima and Nagasaki look gray and frozen, as though they’d been scoured by some awful polar wind. Actually, they were purged by a fire so intense that their inhabitants were vaporized by it. Their last breaths set fire to their lungs as their eyeballs melted.

A mother takes her baby to suckle her breast; the world roars, explodes; for a microsecond, they are linked joints of cooked meat; for another, white-hot bones; then they are gone, particles of dust whirled away in the exhale of the holocaust.

At the square-mile epicenter of the blast, the heat would have melted granite. Most of the buildings in Hiroshima were made of wood.

Twenty minutes after the initial explosion, while the mushroom cloud towered and boiled above the city, while the fires raged, rain began to fall on the remains of western Hiroshima. It was black rain, and radioactive, and it continued for two hours.

One hundred and forty thousand or so people were killed by the bomb. Most died either during the impact or within the following two weeks, of burns or other radiation injuries. For several days, a southerly wind blowing across Hiroshima carried with it a smell like burning fish.

There were survivors, of course. Some were unwise enough to flee southwestward to the city of Nagasaki, upon which, three days after Hiroshima, the Americans dropped an even bigger bomb.

Nuclear weapons go on killing long after the fires have gone out and the toxic fallout has settled. Within weeks of the bombings, people in the environs of Hiroshima and Nagasaki began to sprout keloids, grotesque rubbery scars that claw and spread across the surface of the body and face. The incidence of these disfiguring growths peaked in the years 1946 and 1947, after the war was over. Babies of mothers exposed to radiation were born deformed or were condemned to early death from diseases of the nerve and brain tissue. Eye disorders, especially cataracts, became increasingly commonplace. The long legacy of nuclear bombing is, of course, cancer. By the mid-1950s, Japan had more people dying from leukemia than anywhere else in the world. And for a very long time, the fields around the two cities produced poisonous harvests.

For all this, the Hiroshima and Nagasaki bombs were feeble squibs compared to the infernal firecrackers that Kennedy and Khrushchev had at their disposal in 1962. Nuclear warheads are measured in tons, kilotons, and megatons. A ton, here, is not a measurement of weight; it’s a measurement of blast power. It’s the equivalent to the bang you’d get from a ton of high explosive. A ton of trinitrotoluene, or TNT, which was the stuff in the bombs used during the Second World War. A ton of TNT will make a very big hole in the ground, or demolish a large factory, or erase a neighborhood. A kiloton produces an explosion equivalent to a thousand tons of TNT. The Hiroshima bomb was about thirteen kilotons. More than enough to convert a city into a furnace. But, as I say, it was a baby compared to what came later. A big, ugly baby. And quite primitive, really. It was ten feet long and weighed nine thousand pounds. It looked like a small whale with only tail fins. The humorous Americans called it Little Boy. (And the Nagasaki bomb Fat Man.) It took two dozen technicians three days to complete the nerve-racking task of assembling its various parts, arming it, locking in its safety devices, and loading it into the belly of a B-29 bomber. (The plane was called Enola Gay, after the pilot’s mum. Cute.) Then it took six and a half hours to fly it to its target from the Pacific island of Tinian. All very laborious and troublesome.

But such is the furious inventiveness of man when it comes to weapons of mass destruction that just twelve years later, the U.S. had built enormous rockets — one type called Thor, the other Jupiter — capable of carrying nuclear warheads of one and a half megatons. A megaton, as you will have worked out, explodes with the force of a million tons of TNT. So a single Thor or Jupiter could do as much damage as 115 Hiroshimas, or thereabouts. (You might want to check my figures. I enjoy math, but I’m not terribly good at it. Calculation would be easier for me if I had ten fingers, and I don’t.) If I’m right, that works out to 115 times as many deaths, grotesque disfigurements, deformed babies, cancers, etc., as Hiroshima.

All the same, it wasn’t good enough. Thors and Jupiters couldn’t quite reach America’s enemy, which was the Soviet Union. They certainly couldn’t reach all of the Soviet Union, which consisted of most of the far side of the world, from Germany in the west to Manchuria in the east. And then there was China, which was Communist, too. So, quietly, the Americans placed their huge missiles in friendly countries closer to Russia: England, Italy, Turkey. Places that put Moscow within half an hour of a rocket’s launch.

Even that was unsatisfactory. By the time I was delighted by the belated arrival of my pubic hair, the United States had developed rockets — called Atlases and Titans — that could travel seven thousand miles to dump four megatons of explosive onto Russia. Given the aftereffects of these multiple Hiroshimas — let alone the Soviet response — America had acquired the power to destroy the world several times over.

The Russians were not, of course, sitting idly by while all this was going on. They’d built and exploded an atomic bomb of their own by 1949. The Americans were shocked by how quickly the Communists had caught up. (They didn’t know, then, that Soviet spies were embedded in their weapons research projects.) By the 1950s, it seemed that, as far as rockets were concerned, the Soviet Union had pulled ahead in the arms race. Or at least in the space race, which, in the eyes of many Americans, was the same thing.

In early October 1957, the Russians fired the first man-made object to orbit Earth. It was a small satellite called Sputnik 1.

A month later they launched Sputnik 2. On board was the first living mammal to journey into space. She was a small, bright-eyed, black-and-white dog called Laika.

She didn’t make it back. She was already dead when Sputnik 2 burned up on reentering Earth’s atmosphere. The first man in space did make it back, however. He was a Russian called Yuri Gagarin. On April 12, 1961, his spacecraft made a single orbit of the planet in 108 minutes. He was the first human being to see Earth suspended in its dark and awful solitude. Afterward he said, “Earth was blue. There was no God.”

I think I was less impressed by these feats than I should have been. By the time I was twelve, I’d already traveled to various parts of the universe in the company of Dan Dare, Captain Condor, and other heroes of my comics. Compared to battles with the Mekon’s evil empire or the vast mechanical centipedes of Zardos, a satellite the size of a beach ball and an incinerated dog seemed pretty unimpressive. But I was sixteen when Gagarin circled the earth, and his words gratified the narky little atheist I’d then become. I read them aloud to my grandmother, sadly announcing the nonexistence of God. Her reaction disappointed me.

“I shunt be surprised,” Win said placidly, “if that Rushun wunt lookun the wrong way.”

While Win and I took the Soviet conquest of space calmly, America and the rest of the so-called Free World didn’t. Russian satellites! Russians in space! It was just a tiny step of the imagination to get to Russian satellite missiles in space! My God!

When Gagarin’s spacecraft passed over the U.S., it was less than two hundred miles up. No distance at all! Commuting distance. From that height, a tiny puff of rocket fuel could send all hell down on America’s head. The U.S. Paranoia Meter swung into its red zone.

Then the Russians created the biggest man-made explosion in the history of humanity (so far).

A few months after Yuri Gagarin had landed and confirmed the nonexistence of God, a Soviet Tupolev took off and flew north into the Arctic Circle. It carried, like a gross and ugly pregnancy — so big that the doors of its underbelly had been removed to accommodate it — a huge nuclear bomb. Five miles above the frozen wastes, the crew released it, suspended from a vast parachute. Two and a half miles from the surface of the earth, it exploded with a force of fifty megatons. Fifty million tons of TNT. Ten times the total power of all the explosives used by all sides in the six years of the Second World War. When it was detonated, it created a fireball five miles in diameter. Its base touched the ground and melted it. Its crown reached the altitude of the plane that had dropped it. It was like the invasion of a furious planet. It was like the ferocious roar of God (had He existed). Dropped onto the inhabited parts of the world, it would have stopped civilization in its tracks.

Which was all to the good. It meant that the U.S. and the Soviet Union each had the ability to annihilate the other. Therefore — in theory, at least — neither of these growling superpowers would dare attack the other, because to do so would result in its own immolation.

That was the basis of peace while I was growing up.

It was called Mutually Assured Destruction, or MAD.

MAD has worked fairly well, I guess. I mean, here we both are, me writing, you reading, both of us breathing. It was delicate, though. The thing about MAD is that it depends upon powerful people being sane. That nobody sensible would actually want to convert to lifeless ash the hand that traced the lovely curve of Frankie’s breasts and belly in the gathering darkness of a Norfolk barn. Or turn to radioactive vapor a mother and child in Minsk or Memphis. Unfortunately, however, weapons of mass destruction tend to attract maniacs: men — it’s almost always men — who want to jab the red button and yell, “Take that, you heathen infidel bastards!” and sit in their revolving leather chairs in their underground lead-lined bunkers or caves, watching World War Three or the Final Jihad or whatever on their monitors. Watching Anchorage and Islamabad, Istanbul and Aberdeen flicker and vanish.

Unluckily, in 1962, America’s nuclear arsenal was under the command of just such a man.