There is a small piece of metal sitting today in a glass case on the second floor of the Smithsonian National Air and Space Museum in Washington. It is about 4 in long. It is the color of dull brass. It is shaped like the nose of an artillery shell because that is what it is.
There is a small printed card next to it written in the careful neutral language of museum curators. The card explains that the device on display is a cutaway sample of what was once called a variable time fuse and that for most of the Second World War, the existence of this object was protected at a level of classification that was at the time exceeded only by the Manhattan Project.
The card does not tell you what the object did to the men on the receiving end of it. There is no clean way to put that on a museum card. This story is about that fuse. It is about the few hundred American physicists, engineers, and factory workers who built it. It is about the colonel in Belgium on the morning of December 16, 1944, who made the decision to fire it for the first time on land against direct orders from Supreme Allied Headquarters.
It is about the German soldiers who walked into its air bursts in the snow of the Arden and could not understand after 6 years of total war and two years on the Eastern Front what kind of weapon was killing them. And it is about the moment a few weeks later when intelligence officers in the allied rear began reading the prisoner of war interrogations and realized that the German army did not have the words for what had happened to it. Let us begin with the problem.
In the late 1930s, gunnery officers in every major navy on Earth were arguing about an arithmetic problem they could not solve. An attacking aircraft moved at 300 mph or more. An anti-aircraft shell fired at it from a 5-in gun took roughly 12 seconds to reach the altitude where the aircraft would be.
The gunner therefore had to predict 12 seconds ahead where the airplane would be. Point his gun at that empty piece of sky and fire. If his estimate was off by even a fraction of a second, the shell would miss by hundreds of feet. But missing was only part of the trouble. Even if the shell got close, it had to actually explode at the correct moment to do any damage.
The standard anti-aircraft fuse in 1939 was a mechanical clock, a small wheel inside the shell, hand set on the gun deck just before firing, would run down for the calculated number of seconds, and trigger the detonator. If the gunner had set the timer correctly, and the airplane had moved exactly as predicted, the shell would burst close enough to do damage.
If anything was wrong, and something was almost always wrong, the shell either exploded harmlessly far below the target or sailed past and detonated where it could hurt no one. By American naval estimates from the early war years, gunners firing timefused shells from a 5-in gun had to send up close to 1,000 rounds for every aircraft they actually destroyed.
What every navy in the world wanted and had wanted since the airplane first crossed a battleship was a fuse that did not require the gunner to predict the future. A fuse that could feel the airplane on its own that knew when it was close to its target that detonated automatically the moment the target was within killing distance.
Engineers called it a proximity fuse. They also called it impossible. To make one work, you had to take a sensitive electronic instrument, miniaturize it down to the size of a small fist, and seal it inside the nose of an artillery shell. That shell would then be fired out of a gun barrel under acceleration of up to 20,000 times the force of gravity.
While accelerating, it would be spinning at around 25,000 revolutions per minute because the rifling in the gun barrel made it spin, which was what kept it stable in flight. The instrument inside, after enduring all of that, had to switch on, work perfectly, and detect a target moving past at 300 mph from a distance of 70 ft.
And it had to be cheap enough to mass-produce because the shells were expendable and would be fired by the millions. In the 1930s, German engineers studied this problem and gave up on it. The Japanese gave up on it, too. The Americans had not even seriously begun. The British alone refused to give up. At a research facility in southern England called the telecommunications research establishment, four scientists, William Butt, Edward Shia, Amherst Thompson, and Samuel Curran kept working on the idea through the early years of the war and
eventually got a crude prototype to function inside a slowmoving rocket. But Britain in 1940 had no industrial capacity to spare. The factories were busy making aircraft and tanks and ships. There were no spare engineers, no spare assembly lines, and the British physicists themselves were not certain a working version could ever be built for an artillery shell.
The forces inside the shell were too violent. The electronics they thought would simply shatter. In September 1940, a small British scientific delegation led by the physicist Henry Tizard sailed to the United States with what they called the deed box, a small lockable metal trunk full of secrets. Inside that trunk was almost the entire scientific portfolio of the British war effort.
The cavity magnetron that would make modern radar possible was in there. The blueprints for the jet engine were in there, and so was a stack of papers describing the early experiments on the proximity fuse. The British, knowing they could not produce these things alone, were handing them to the Americans in exchange for the only thing the Americans could give them faster than anyone else, which was factories.
A few weeks later, an American physicist named Merl Tuve, who at that point was working at the Carnegie Institution of Washington as a respected but obscure researcher in nuclear physics and radio wave studies, was put in charge of a new project. The project was so secret that it would never officially have a name. It would simply be called Section T after the first letter of his last name.
Section T’s job in a single sentence was to do what every other major military power had decided could not be done. It was to put a working radio transceiver inside an artillery shell. Tou was 39 years old. He was not a corporate man. He was not a politician. He was a tall, plain spoken physicist from South Dakota with a short temper, a relentless work ethic, and a famous intolerance for bureaucratic delay.
He recruited every miniaturization specialist he could find. He pulled in engineers from the radio industry, from the hearing aid industry, from the electric razor industry. The hearing aid people, it turned out, were the most useful because they had spent years trying to make vacuum tubes small enough to fit behind a deaf man’s ear.
By Tuve’s order, every one of those tubes was to be taken apart, examined, redesigned, and rebuilt to survive being shot out of a cannon. One of the young men Tuveet brought in was a 27-year-old physicist from Iowa named James Van Allen. Van Allen had been working at the Department of Terrestrial Magnetism studying the upper atmosphere.
He was tall, quiet, and methodical. He was not at that moment a famous man. He would become famous a decade and a half later when satellites bearing his instruments discovered the bands of trapped radiation now named for him that surround the Earth. But before Van Allen could be the man who mapped the radiation belts, he had to spend three years figuring out how to build a vacuum tube that would not shatter when fired out of a 5-in naval gun.
The vacuum tubes he and his colleagues at the Applied Physics Laboratory eventually developed used a tiny internal spring suspension designed to hold the delicate electrodes in place under 20,000g. Years later, when Van Allen needed instruments that could survive being fired into space on top of a rocket, he would draw directly on what he had learned soldering proximity fuses during the war.
The fuse, in other words, would be the doorway into the space age. But that was a story for after the war. In 1942, all anyone wanted was a device that would shoot down a Japanese dive bomber. The principle they eventually settled on was elegant in the way only good engineering ever is. Inside the nose of each shell sat four miniature vacuum tubes, a battery, a small antenna, and a transmitter.
The transmitter sent out a continuous radio wave at a frequency between roughly 180 and 220 megahertz using the metal body of the shell itself as the antenna. As the shell flew toward its target, that radio wave bounced off any solid object in its path and returned to the transmitter. When the shell got close enough to the object within about 70 ft, the returning wave produced an interference pattern in the transmitter that varied with distance.
A simple electronic filter inside the shell read that pattern and at the precise moment the math said the target was closest triggered the detonator. The whole process took place over the last fraction of a second of the shell’s flight. The man on the gun crew never knew. He simply pulled the lanyard and the shell somewhere over the enemy decided for itself when to explode.
In the spring of 1942, section T was transferred from the Carnegie Institution to a new home, a freshly built laboratory in Silver Spring, Maryland, run as a wartime contract operation by John’s Hopkins University. They called it the Applied Physics Laboratory. By 1944, the project would involve over 100 manufacturers, 26 prime contractors, and roughly 10,000 workers.
It would burn through over $1 billion in 1940s money, which is roughly $15 billion in today’s currency. Procurement contracts climbed from $60 million in 1942 to 200 million in 1943 to 300 million in 1944, peaking at 450 million in 1945. A General Electric plant in Cleveland, Ohio that had been making Christmas tree lights and miniature lamps now spent its days making the glass envelopes for fuse tubes.
The Crosley Radio Corporation in Cincinnati, the Eastman Kodak Company in Rochester, the McQuay Norris Piston Ring Company in St. Louis, and the Sylvania Electric Works in Ipsswitch, Massachusetts, became the five primary assemblers. Behind them sat a network of more than 2,000 subcontractors, ranging from powder manufacturers to small machine shops in towns nobody outside of central Pennsylvania could find on a map.
By the end of the war, the Sylvania plant in Ipsswitch alone had produced over 5 and a half million fuses, more than any other location in the country. The women on the Ipswich line were told they were soldering small radio components for the Navy. They were not told what the radios were for.
They worked under blackout curtains. They were forbidden to discuss their jobs, even with their husbands. Some of them, when interviewed many decades later by local historians, said they had assumed the components were going into ordinary radio receivers for ships at sea. A few said they had thought they were soldering parts for radar sets.
None of them guessed that they were assembling the firing mechanisms for what were about to become the most lethal artillery shells of the war. There is a small detail in the Ipsswitch town historians records that says everything you need to know about how the secret was kept. After the war ended, several of the women were diagnosed with serious illnesses, including in at least one documented case, malignant meaththeloma, traced to chemical exposures inside the Sylvania building.
When their doctors asked them what they had worked on during the war, the women answered that they did not know. They said it had been classified and that they had thought at the time that they were making the tips of light bulbs. The reason every one of those workers had to be kept ignorant of what they were actually building is the second piece of this story.
By 1942, section T was no longer just trying to make a weapon. It was trying to make a weapon that the Germans must under no circumstances be allowed to discover. The fear at the heart of this secrecy was simple. If a single intact fuse fell into German hands, German engineers, who were among the most sophisticated electronics specialists in the world, would reverse engineer it.
They might then design countermeasures, jammers that would render the fuseless. Worse, they might build their own version. And if the Germans had a working proximity fuse in their anti-aircraft batteries, the Allied bomber crews already taking heavy casualties over Europe would be cut to pieces. the daylight bombing campaign would simply collapse.
So, the rule was set. The proximity fuse, code named VT for variable time, a deliberately misleading name suggesting it was just a more accurate clock fuse, would only be fired in places where if it failed and fell as a dud, it could not be recovered by enemy hands. In practice, this meant water. The fuse would be used by the United States Navy at sea. It would not be used over land.
The first combat use came on the morning of January 5, 1943. The light cruiser USS Helena operating off the island of Guadal Canal was attacked by a flight of Japanese Ah3 a dive bombers called the Val by Allied pilots. A young lieutenant aboard Helena named Cochran was in command of the after 5-in battery.
He had been issued a small number of the new shells but had been given strict orders about how to use them. When the valves came in, Cochran fired three salvos. The third of those salvos brought a val out of the sky. The shell did not strike the aircraft. It burst nearby in midair, and the cone of shrapnel did the rest.
Within minutes, Helena’s gunners had brought down two valves, using a fraction of the shells that conventional doctrine would have predicted they needed. Word traveled fast through the Pacific Fleet. James Van Allen himself, by then a Navy lieutenant, sailed on destroyers through the South Pacific for 16 months, explaining the new fuse to gunnery officers and persuading them to trust it. Many crews were initially reluctant.
They feared the sensitive electronics would detonate the shell prematurely inside the gun, killing the gun crew. Van Allen had to demonstrate on deck after deck that a small mechanical safety inside the fuse prevented the device from arming until about half a second after the shell left the barrel, by which time it was already hundreds of feet from the ship.
Slowly, ship by ship, the Navy converted. By the spring of 1944, the fuse was standard equipment for 5-in anti-aircraft fire across the Pacific. The results were brutal. Across the great battles of the Pacific in 1944 and 1945, the kamicazi attacks of the Philippine Sea, of Lee Gulf, of Okinawa, the proximity fused shells of the United States fleet broke up Japanese formations the way nothing else had.
Vanavar Bush, the head of the Office of Scientific Research and Development, would later credit the proximity fuse with a seven-fold increase in the effectiveness of 5in anti-aircraft fire. By the time of the Battle of Okinawa in the spring of 1945, the fuse was the single most important reason American ships were surviving Japanese suicide attacks.
Secretary of the Navy James Foresttol would later state plainly that without the proximity fuse, the westward advance across the Pacific could not have been so swift, and the cost in men and ships would have been immeasurably higher. And yet the rule held. Throughout all of this, the fuse was not to be used over land.
The Pentagon enforced the prohibition. The combined chiefs of staff enforced it. The United States Army Air Force’s command, terrified of what would happen to the bomber crews if the Germans ever recovered an intact fuse, enforced it most stubbornly of all. Eisenhower, who had been briefed on the device and could see clearly what it might do for his ground forces, argued against the ban repeatedly and was repeatedly told no.
Every senior artillery officer in the European theater who knew about the device understood that the most lethal anti-personnel munition ever invented was sitting in storage in the rear and they were forbidden to load it. This iron law could not survive the summer of 1944. In June 1944, the Germans began launching V1 flying bombs at London.
The V1 was a small jet powered missile pilotless carrying a 1-tonon warhead flying at around 400 mph. It was launched from sites on the French and Dutch coasts. Over the course of the campaign, thousands were eventually fired. They were not aimed at military targets. They were aimed at the city of London itself with the deliberate intent of breaking civilian morale.
They killed roughly 6,000 people in southern England and injured close to 18,000 more. British and American anti-aircraft gunners trying to shoot the V1s down faced a problem similar to the one their counterparts at sea had been struggling with for years. The V1 was small, fast, and on a fixed trajectory. Conventional time fused flack fired in massive barges at predicted points was bringing down only about one v1 in six.
In the early weeks, the Royal Air Force tried sending fighters up to chase the missiles, but the V1s flew nearly as fast as a Spitfire on the level, and the only reliable way for a fighter to bring one down was to fly alongside it and tip it over with its wing tip, a maneuver requiring extraordinary skill and considerable luck.
The combined chiefs reluctantly approved the use of the proximity fuse in British and American anti-aircraft batteries along the southern English coast. The reasoning was simple. The guns would be firing out over the English Channel. Any dud shells would fall into the sea. The Germans could not recover them. The risk of compromise was at last acceptable. The result was immediate.
Within a few weeks of the proximity fuses being deployed in the coastal belt, the kill rate against V1s rose from around 17% to nearly 80%. On one of the last days of Major V one launches against England, radar tracked 104 missiles approaching the coast. 68 were destroyed by proximity fused shells. Of the rest, only four reached London.
Churchill himself wrote afterward that the American fuses had proved potent against the small unmanned aircraft with which we were assailed. Then in September 1944, the Germans began launching V1s at the Belgian port of Antworp, which the Allies had recently captured and which was crucial for resupplying the advance into Germany.
The proximity fuse was approved for use in the Antworp defenses, too. A single American anti-aircraft battalion on the V1 approach lanes destroyed 48 of the first 75 missiles it engaged. By the end of the war, anti-aircraft batteries around Antworp would account for over 2,000 V1 kills.
The wall of secrecy was beginning to crack. On October 25, 1944, the combined chiefs of staff approved the use of the proximity fuse over land in an anti-aircraft role, but they still refused to release it for use in field artillery, where shells would explode over enemy ground troops and could be recovered by the enemy as duds.
The ban held until the morning of December 16. That morning, at 5:30 hours, the German army launched the largest offensive on the Western Front since the invasion of France in 1940. 1,600 artillery pieces opened fire across an 80m section of the American line in the densely forested Arden.
Behind that barrage came roughly seven Panza divisions and around 13 Volks grenadier and infantry divisions crashing into a thinly held front held by four American divisions. Three of those American divisions were either green and untested or shattered units pulled back to refit. The fourth was armored and overstretched. The Germans achieved complete tactical surprise.
Among the units in the path of the assault was the United States 38th Cavalry Reconnaissance Squadron, which was lightly armed and dug in around the Belgian town of Mona on the northern shoulder of the offensive. The 38th Cavalry was a screening force. It was not built to absorb a Panza core. As the German assault opened, the squadron came under attack from the German 326th Volk Grenadier Division and was being overrun.
They called for artillery support. The man on the receiving end of that call was Colonel Oscar A. Axelson, commanding officer of the United States 405th Field Artillery Group. Axelson was sitting on a stockpile of newly issued shells fitted with the proximity fuse. The Pentagon had cleared the shells to be shipped to forward artillery dumps in Europe in case they were needed, but no permission had been given to actually fire them.
In Axelson’s possession that morning was a written directive, making it explicit. The fuses were to be held in reserve. They were not to be used unless authorization came from Supreme Allied Headquarters. What Axelson did next by any normal reading of military regulations was a court marshal offense. He gave the order to fire the proximity fused shells code named posit in army usage in support of the 38th cavalry.
He did not call supreme headquarters. He did not request clearance. He looked at the cavalry troopers being overrun, looked at the secret weapon sitting in his ammunition dumps, and made the decision a colonel is not supposed to make. The first proximity fused artillery shells fired against ground troops on the European continent, fired by the 196th Field Artillery Battalion under Axelson’s command, came down on the German 326th Folks Grenadier Division.
A few minutes later, they burst on average between 30 and 50 ft above the German positions. They cut down troops in the open. They killed men in foxholes. They penetrated log roofed dugouts in a way no time fused artillery had ever managed. Within the hour, the German attack on the Mona sector had stalled.
3 days later, on December 19, Eisenhower formally requested that the combined chiefs lift the embargo on land use of the proximity fuse. Two days after that, all restrictions were lifted. 200,000 posit fused shells were released for general use in the Battle of the Bulge. For the German soldier on the receiving end, the experience was apocalyptic.
If your father or grandfather served in the artillery in the European theater or in the Pacific, I would be honored to hear his name and his unit in the comments below. The men who fired these guns are mostly gone now. The story of what they did and what their officers did at moments like the one Axelson faced on the morning of December 16 deserves to be remembered with all of the names attached.
To understand why the German prisoners taken at the bulge could not explain what had happened to them, you have to understand the shape of standard German anti-artillery doctrine and you have to understand what the proximity fuse did to it. A German infantry company in 1944 was by long training very good at surviving artillery.
The doctrine was layered and detailed. When a barrage was incoming, men dispersed and got low. They preferred foxholes with a small overhead lip of dirt. If they had time, they constructed log roofed dugouts, what the Vermacht engineering manuals called unstand with timbers strong enough to absorb the lateral blast of a shell exploding nearby on the ground.
In static front lines on the Eastern Front, German engineers had built up entire fortification networks based on this principle. The basic logic was simple. Shells fired by enemy artillery had to physically strike the ground to detonate. When they did, most of the shrapnel and concussion went outward and slightly upward in a low cone.
A man flat in a hole with even a little bit of overhead cover was relatively safe. Timefused shells in theory could explode in the air and pose a threat to a man in a foxhole, but in practice they almost never did. To get a timefused shell to explode at the right altitude over a precise enemy position required a forward observer with a clear view of the target, careful range calculation, and dozens of ranging rounds to walk the bursts down to the right height.
In the Arden in December 1944, weather conditions made all of this nearly impossible. Heavy fog and overcast skies kept Allied observation aircraft on the ground. American forward observers on the ridges had visibility measured in tens of meters, not kilome. The Germans had launched the offensive precisely because the bad weather meant that Allied air power and Allied artillery observation would be neutralized.
Or so it was supposed to work. The proximity fuse rendered all of that calculation obsolete in a single afternoon. The fuse did not require a forward observer. It did not require a clear line of sight. It did not require ranging rounds. The gunner simply set his shell to air burst mode, fired in the general direction of the enemy formation using map coordinates, and the shell on its own sensed the ground rushing up at it and detonated at the optimal height.
The cone of shrapnel that came down was not lateral. It was vertical. It rained down from above, and it found men lying in shallow foxholes the way water finds the bottom of a bucket. A German infantryman who had spent years training to survive artillery was, in the literal sense, defenseless.
The drill of dropping flat and getting low was not just useless. It exposed his back to the shrapnel coming from above. A log roof, which could survive a near miss on the ground, was punched through by fragments hammering down vertically at high velocity. Slit trenches became death traps. Bunkers without overhead concrete became death traps.
Open ground was, of course, the worst of all. Whole companies caught in the open during a proximityfused bombardment ceased to exist as fighting formations within minutes. There was a second effect, more subtle, but in the long run equally devastating. Time fused and contactfused artillery when fired into a forest, often detonated against the upper canopy of trees or struck the trunks of large pines.
Shrapnel sometimes scattered downward through the branches, but most of the destructive energy was absorbed by the wood. German troops in the heavily wooded sections of the Arden had assumed, with good reason, that they were relatively safe from artillery. As long as they stayed under tree cover, the proximity fuse ignored the trees entirely.
It detonated at its programmed height regardless of what was underneath, raining shrapnel through the canopy and onto the men below. Forest cover, which had protected German soldiers throughout the war on the Eastern Front and in the early stages of the Western campaign, was suddenly worthless. American intelligence summaries compiled in the weeks after the battle.
Quote, German prisoners describing a single common phenomenon. The shells came without warning. There was no whistle because by the time the sound caught up, the shell was already passed. The first awareness any soldier had of the fuse coming for him was the crack of a burst directly overhead. And then the sound that veterans of every front in this war would later describe as unique.
the sound of metal striking the ground at high speed in every direction at once. Some prisoners described the bursts as dazzling. Some described being unable to think, unable to move after only a few minutes of sustained bombardment. In the official report compiled by the eighth infantry division on a later operation in the Herkan Forest, an American patrol caught a German formation in what gunners called a posit time on target mission.
When the patrol moved forward to count the dead, they reported 96 Germans killed by a single concentration. On December 21, the day all restrictions on the proximity fuse were finally lifted, the German SS Lieutenant Colonel Otto Scorzani, the same officer who had rescued Mussolini from his mountaintop prison the year before, attempted to push his Panza Brigade 150 toward the town of Malmi as part of the broader offensive.
His brigade had been raised for an operation called Grafee. The German plan to use English-speaking commandos in American uniforms to seize bridges over the MS. By December 21, the deception part of Grafe had largely failed and Scodzan’s men were fighting as conventional infantry. They walked into proximity fused fire from the American 30th Infantry Division and its supporting artillery.
The attack collapsed. By December 23, less than a week into the wider offensive, American intelligence officers were estimating that proximity fused artillery had killed 2,000 German troops. By the end of the battle, the figure had grown by an order of magnitude. The German army quickly realized it was facing something new.
Patton himself after seeing what proximity fuses did to a German battalion attempting to cross the sour river wrote a letter to Major General Levanh Campbell Jr. the chief of army ordinance. Patton was rarely a man given to understatement but the letter is unusual even by his standards. He wrote that the new shell with the funny fuse was devastating.
He wrote that his gunners had caught a German battalion in the river crossing and had killed 702 of them by actual count. He wrote that he believed the introduction of this fuse would require new tactics for warfare. He wrote in a sentence that was as close as Patton ever came to humility that he was glad the Americans had thought of it first.
In a separate piece of correspondence also forwarded to Campbell, Patton put the matter even more directly. The funny fuse, he wrote, won the Battle of the Bulge. The most important thing about the proximity fuse, in a strategic sense, was no longer what it did to a German company in a Belgian forest. The most important thing was what it did to the German understanding of what kind of war they were fighting.
Through 1943 and into 1944, the German military establishment had been operating on a private assumption that while the Americans had more material, the Germans had a technological lead in almost every area that mattered. The German jet aircraft, the Messid 262, was operational by the summer of 1944 and was faster than anything the Allies could field.
The German 52 ballistic missile, which began landing on London in September 1944, was a weapon for which the Allies had no defense at all. The German submarine fleet, with the new type 21 electroboot designs, was on the verge of producing submarines that could outrun every escort ship in the Royal Navy. The German army had Tiger tanks and Panther tanks that could destroy any Allied armor at long range.
In the German imagination of the war, the Reich would either lose because of weight of numbers, in which case nothing technological could save it, or it would buy enough time for one of these wonder weapons to break the deadlock. The proximity fuse was the first piece of irrefutable evidence that the Germans had lost the technology race in a domain they had assumed they were winning.
The Germans had worked on proximity fuse designs since the early 1930s. By the end of the war, between 30 and 50 different German proximity fuse concepts had been developed or researched. Not one of them ever entered service. The German engineers had concluded, given their industrial constraints, that the artillery shell version was impossible.
They had assumed also incorrectly that since they could not solve it, neither could anyone else. When the first captured American fuses were sent back to German laboratories in late December 1944, a few duds and some partially intact specimens recovered from the snow. The engineers who opened them up were looking at something more disturbing than a new weapon.
They were looking at proof that they had been wrong about the entire shape of the war. The Americans had not just beaten them with quantity. The Americans had solved an electronics problem of the highest difficulty in absolute secrecy. mass- prodduced the solution by the millions and deployed it in time to break a German offensive.
The fuse itself, when laid out on a workbench, contained components, some of which the German electronics industry could not have manufactured at all. The miniature vacuum tubes alone were beyond German production capability in the quantities required. The fuse did not represent a German loss of imagination. It represented a German loss of industrial reach.
There is a piece of strategic accounting that has stuck with every historian who has looked at the secret weapons of the Second World War. The V2 ballistic missile, which the German high command had bet much of its remaining hope on, killed roughly $2,750 people in London and around 1,700 more in the Antworp area. It cost the Reich roughly $2 billion, an investment comparable to the entire Manhattan project, for a weapon that could not be aimed precisely and could not be defended against, but could not be produced in numbers large enough to
matter. The proximity fuse, which fit in the palm of a hand, killed German soldiers in numbers no one ever satisfactorily counted, and it did so cheaply enough that 22 million of them were produced. The flashy weapon was a strategic dead end. The quiet weapon, the one that nobody outside a few American physicists had ever imagined, broke the back of the Vermacht in the field.
In the postwar interrogations of senior German officers, the subject came up over and over. They had assumed that whichever side fielded a ballistic missile in numbers would have a decisive edge. They were wrong on both counts. The missile killed thousands. The fuse killed tens of thousands and changed how a battle could be fought.
A senior German artillery officer captured in early 1945 when asked what he thought of the new American shells reportedly told his American interrogator that German soldiers had been raised to believe German engineering would protect them from American factories. He said the funny shell, as the prisoners had begun calling it, had made it clear that this was no longer true.
He said the Americans had a kind of scientist they did not have. He said he did not understand where these scientists had come from. The answer to the question the German officer was asking is that they had come from places like Iowa, where James Van Allen had grown up tinkering with radios in a small town and would later return to teach physics for 34 years.
They had come from places like the Carnegie Institution where Merl Tuve had spent a quiet decade studying the ionosphere before being asked to help save his country. They had come from hearing aid factories and Christmas tree light plants and small machine shops in Pennsylvania and Massachusetts and Ohio.
They had come from a country that had been throughout the 1920s and the 1930s quietly accumulating a deep bench of practical engineers and tinkerers and small-scale manufacturers, none of whom would have been visible from Berlin. None of whom were doing anything anyone would have called important, but all of whom turned out to be, when the war demanded it, the people who could solve problems no one else thought were solvable.
The proximity feuds did not win the Second World War. By December 1944, the war was already lost for Germany in every measurable way. The Soviet armies were closing on East Prussia. The American and British armies had crossed France and were inside the Reich’s western frontier. The German economy was disintegrating under the weight of strategic bombing.
There was no secret weapon that could change those facts. What the proximity fuse did was something subtler and in some ways harder to absorb for the men on the receiving end. It demonstrated in a way no German soldier could deny that the war they were fighting was not the war they had been told they were fighting.
the doctrine that had carried them across half of Europe, the careful drills for surviving artillery, the trust in cover, in foxholes, in the quiet competence of their officers, had been quietly rendered obsolete by an electronic device the size of a soup can designed in a Maryland laboratory by a few hundred civilians, most of whom would never wear a uniform.
When Eisenhower wrote about the new American weapons after the war, he allowed himself an unusual moment of speculation. If the Germans had succeeded in perfecting and using these weapons 6 months earlier than they did, he wrote, the invasion of Europe would have proven exceedingly difficult, perhaps impossible.
He was in part talking about the V1 and the V2. But he was also talking about the proximity fuse, which the Allies had developed and the Germans had not, and which had shifted the balance of every battle in the last 6 months of the war by a margin no one bothered to calculate. Most of the Americans involved in this story did not become famous.
Merl Touv returned to the Carnegie Institution after the war and went back to studying the ionosphere. He died in 1982, never as well known as his contemporaries on the Manhattan project. James Van Allen went on to discover the radiation belts of the Earth and is remembered for that work, not for the war years that made his later career possible.
Colonel Axelson, who broke the embargo on the morning of December 16, finished out the war and his career without any great public recognition for the decision he made on a snowy Belgian morning. The factory women in Ipsswitch in Cleveland, in Cincinnati, who hands soldered the small components by the millions, never knew until long after the war was over what they had been building.
Some of them learned only when reading newspaper articles in 1946. A few never learned at all. The fuse itself was declassified in pieces over the following decades. Many of the technical reports written by the staff of the Applied Physics Laboratory remained classified into the 1970s. The most detailed compilation of the development history was not made publicly available until the summer of 1976, more than 30 years after the wars end.
The cutaway sample now displayed at the Smithsonian, the small piece of dull brass in its glass case, bears a label noting that it was once protected as one of the war’s deepest secrets. Visitors walk past it every day. Most of them do not stop to read the card, and that perhaps is the truest measure of what these men built.
The atomic bomb left a shadow on the rest of the century. Radar reshaped how we understand the air around us. The proximity fuse, which by some honest reckonings did more day-to-day damage to the veh in the last 6 months of the war than any other single Allied technical achievement, simply slipped quietly into the background of military hardware after 1945 and stayed there.
There is no monument to it. There is no annual anniversary. There is somewhere in a drawer in a museum in Maryland a handful of telegrams from Patton and Eisenhower praising it. And there is a glass case in Washington with a 4-in piece of brass in it. That is more or less all. The men who built it would probably have preferred it that way.
They were not most of them men who needed the credit. They were physicists who liked physics. They were factory workers who needed a job. They were, when you take the long view, the kind of people who solve a problem because the problem is in front of them and then go home. The country they came from was in the years before the war full of such people.
It had not always known what to do with them. The war showed it. And on a snowy morning in Belgium, in the second week of the worst winter of the European campaign, a colonel named Axelson decided he had waited long enough for permission, and the people who had quietly built the impossible thing finally got to see what it could do.
If you have read this far, you are part of why these stories survive. Hit the like button if you would like more of them. Subscribe if you want the next one. There are dozens of these accounts from the Second World War. Most of them about engineers and gunners and infantrymen who never expected to be remembered and who deserve to be.
The truth of what happened in those years is bigger and stranger than the stories most of us grew up hearing. It deserves to be told carefully with all the names, all the details and all the inconvenient facts intact.
