German Gunners Couldn’t Explain Why American Shells Were Bursting in the Treetops

In the last week of December 1944, in a stand of frozen pine east of Baston, a German grenadier lay in a hole he had cut into ground so hard the entrenching tools rang on it. And he understood exactly what was keeping him alive. He understood the fog. It had sat on the Ardens for a week, a low gray ceiling that had grounded every Allied aircraft in Northwest Europe.

And for a soldier who had spent the autumn being hunted from the air by fighter bombers he could hear but never see in time. That ceiling was the finest thing the winter had given him. He understood the hole. A hole in the ground is one of the oldest solved problems in war. A shell that lands on the earth throws its fragments up and out in a low flat fan.

And a man below the level of that fan is not in the fan. He had been taught the arithmetic of it in training. And then he had been taught it again by four years of surviving. And he trusted it the way a man trusts a floor. So when the American guns opened, he did what he had always done, which was to get low and wait for it to be over.

The shells did not land. That is the part he could not put anywhere. They came in with the sound he knew, and then they stopped 20 ft up, 50 ft up, above the pines, and above his hole. And they burst there in the air over open ground where there was nothing to burst against. And the fragments came down, not out, down, into the hole, onto the men beside him, into the one place on the whole battlefield that had always been safe.

Every man on that ridge came to the same conclusion because it was the only conclusion available. The Americans had found some way to make every single shell burst in the treetops. everyone on the first round without ranging in fog in the dark overground with no trees on it at all. They were wrong.

What was above them was not a trick of gunnery. And it was not a new kind of tree burst. It was a radio and a battery made of glass and five vacuum tubes the size of a man’s thumb packed into the nose of an artillery shell and sold to the world under a name that was a deliberate lie. This is the story of the proximity fuse.

of the two years it spent locked up under a security order that forbade the army from firing it over land and of the word that came over the wire in December 1944 that unlocked it. By the end of this you will know that word. You will know the phrase General George Patton put in a letter to the chief of ordinance about what it did to the Germans in front of him.

and you will know what the prisoners taken in the Ardens told their American interrogators they believed was happening to them which is the closest thing we have to a verdict from the men who were underneath it. Start with the ground because the ground is why the fuse mattered here and not somewhere else.

The Ardens in December 1944 was a country of steep wooded ridges, narrow roads and deep snow held in a weather system that behaved like a weapon. Fog every morning, low cloud that did not lift. temperatures that froze the grease in machine guns and the fuel in trucks. From the 16th of December, when the offensive opened until the sky finally broke on the 23rd, Allied air power was effectively absent from the battlefield and every German commander in the operation had planned on exactly that.

The weather was not a piece of luck. It was a scheduled component of the plan. What that left was artillery. In fog and darkness, the American observer could not see the target. The fighter bomber could not fly, and the tank could not identify what it was shooting at. The howitzer could still fire because a howitzer does not need to see anything.

It needs a map, a survey, and a set of numbers. The trouble was what the shell did when it got there. Understand that the German soldier’s confidence was not stupidity, and it was not propaganda. It was arithmetic and it had been right every time he tested it. A 105 mm shell with an ordinary point detonating fuse strikes the earth and detonates at ground level.

And a large part of its energy goes into the earth and a large part of its fragmentation goes upward at an angle. Against men standing in the open, it is murderous. Against men lying flat, it is much less so. Against men in a hole, it is close to useless, unless the round lands almost on top of them. Soldiers on every front had learned this and dug accordingly.

And the deeper the hole, the more the arithmetic favored the man in it. There was only one answer to a hole. And every artillery officer in every army knew what it was. You do not try to hit the hole. You burst the shell in the air above it. So the fragments come down through the opening at the top.

The Americans had a way of doing that, and the way was bad. It was called a time fuse, and it worked exactly as it sounds. Before firing, a crewman set a mechanical ring on the nose of the shell to a running time. So many seconds, so many fractions of a second, and the fuse burned or ran down and detonated the shell when the time expired.

To put that burst at the right height over the right ground, you needed the range solved precisely. The muzzle velocity of that particular worn barrel accounted for the air temperature and the powder temperature and the wind aloft. And then you needed a forward observer who could see the bursts and correct them, walking them down or up until the height was right.

Registration rounds first, then correction, then fire for effect. Every part of that was expensive. It took time, which in a moving fight is the thing nobody has. It gave away the intention because the ranging rounds told the enemy that something larger was coming and roughly where. It burned ammunition on shells that were not yet hitting anything, and it depended entirely on an observer with eyes on the target, which in an Arden’s fog at 3:00 in the afternoon in a pine forest meant it depended on nothing.

Even done perfectly, it was inconsistent. Fuses varied, barrels varied. A battery firing a time fuse mission scattered its bursts through a range of heights. Some too high to be worth much, some low enough to hit the ground and be wasted, and only a portion in the band where they did what they were meant to do.

There was a second method, and it was the reason the German assumption about treetops existed at all. In heavily wooded country, you could fire ordinary point detonating rounds into the crowns of the trees and let the trunks and branches do the fusing for you. The shell hit a tree 50 ft up, burst there, and rained fragments and splintered timber onto everything below.

The Americans and the Germans both used it and both feared it. And in the Herkin forest that autumn, it had done frightful work in both directions. That is why when the shells started bursting overhead in the Arden, the German soldier reached for the explanation he had. Tree bursts. The Americans have got very good at tree bursts.

The explanation collapsed the moment the same thing happened over a snowfield with nothing standing on it. The thing in the nose of those shells had begun as an idea nearly everybody in the business considered impossible, and it had come to the Americans partly as a gift. In 1940, when Britain was alone and expected to be invaded, a delegation under Sir Henry Tizzard crossed the Atlantic carrying the best of British military science in a black metal box and handed it to a country that was not yet in the war.

Most of the attention goes to the cavity magnetron, which made centimetric radar possible. In the same package was British work on a fuse that would sense its own approach to a target and fire itself. The idea was old and the engineering was thought to be beyond reach. Put a small radio transmitter and receiver in the nose of a shell.

Have it broadcast continuously and listen for its own signal coming back off whatever it is approaching. As the shell closes, the returning signal shifts and strengthens in a way the circuit can recognize. And at the right moment, the circuit closes a switch and detonates the round. On a laboratory bench with unlimited time, this is difficult.

In an artillery shell, it is close to absurd. And here is why. When a 5-in naval gun fires, everything inside the shell is subjected to an acceleration in the region of 20,000 times gravity. A glass vacuum tube weighing a few grams briefly weighs the equivalent of a sack of cement. Then once clear of the muzzle, the shell spins on its axis at hundreds of revolutions per second to keep it stable, which throws every loose component outward with enormous force.

The device had to survive both, then work reliably seconds later, having sat in a magazine or a shell dump for a year beforehand. The work went to section T under the National Defense Research Committee and then to the Applied Physics Laboratory at John’s Hopkins under a physicist named Merurl Touve. What his people did was solve the problems one at a time in ways that sound like improvisation and were not.

The tubes came down from the hearing aid industry which already made the smallest vacuum tubes in the world and then were rebuilt with heavier internal supports and shortened elements until they could take the setback shock. The battery was the elegant one. An ordinary battery sitting in storage for months goes flat.

And no army wants ammunition whose fuses have quietly died in the crate. So they built a battery with no electrolyte in it. The acid sat sealed in a small glass ampule inside the fuse, chemically separate and indefinitely stable. The shock of firing shattered the ampule and the spin of the shell flung the liquid outward into the plates and the battery came alive somewhere in the first fraction of a second of flight.

The fuse was dead in the box and dead in the breach and only became a live electronic device once the gun had already fired it. Then they named it. Somebody decided the security of the thing would be helped by a name that told a listener the wrong story. And so it was called the VT Fuse for variable time. Anybody who overheard the term would assume it was a refinement of the time fused the world already knew about.

It was nothing of the kind. The deception was built into the vocabulary from the first day. The scale of what followed is not widely appreciated. The program ran to roughly a billion dollars of wartime money and something in the order of 22 million fuses made by firms including Cley, Sylvania, General Electric, Eastman, Kodak, and RCA, factories that had been making radios and camera parts and hearing aids and were now turning out a precision electronic assembly designed to be destroyed on first use.

Vanavar Bush, who ran American wartime science, put it alongside radar and the atomic bomb in the front rank of what the laboratories had delivered. And for two years, the army in Europe was forbidden to fire it at the ground. The reason was sound, and everybody hated it. A fuse that goes off in the air destroys itself.

A fuse that fails and a proportion always fail falls to Earth substantially intact. If that happened over water, the fuse went to the bottom and was gone. If it happened over enemy held land, a German technician would in due course be holding an American radio proximity fuse in his hands. And the Germans had their own proximity fuse research running and lacked only the manufacturing solutions the Americans had spent 2 years finding.

The nightmare was specific and it was not paranoid. Allied bomber streams were flying daily over German anti-aircraft belts. A German 88 firing shells that burst automatically at the correct height inside a bomber formation would have raised the cost of the air campaign to something unbearable. So the fuse went to sea first where dud sank.

On the 5th of January 1943, the cruiser USS Helena in the Solomons brought down a Japanese aircraft with a proximity fused 5-in round, the first kill of its kind. Naval anti-aircraft gunnery was transformed inside a year. Then it went to England. In the summer of 1944, the V1 flying bombs came over in numbers, and the gun belt on the South Coast was firing at a small, fast machine, flying a straight line at a constant height, which is the perfect customer for a fuse that only has to be close.

Combined with SCR584 gun laying radar and the M9 electrical director, the results at the end of that campaign were extraordinary, with the great majority of the bombs entering the belt destroyed before they crossed it. Duds fell in the channel and in English fields the army controlled over the front line in France and Belgium it stayed locked.

Field artillery officers knew it existed. They knew what it would do to infantry in the open. They were not allowed to have it. The Ardens broke the lock. Accounts differ slightly on the precise date the authorization took effect and that is worth saying rather than hiding because you will see different days given in different books.

What is not in dispute is that in the second half of December 1944, with two German armies driving west through the American center and the weather keeping the Allied air forces on the ground, the restriction on ground use in Europe was lifted and the artillery battalions were told they could fire it.

The word that went out to identify it was pose it. That was the code word and it went onto the fire missions and into the radio traffic. And to a battery executive who had spent months hearing rumors, “Pose it meant one thing. Fire it. Do not range it. Do not adjust the height of burst. Do not wait for the observer to walk it down.

Send it and it will burst where it needs to burst.” What made it so violent in that particular fight was the combination of things it removed. It removed the ranging. A time fuse mission announced itself. A proximityfused mission arrived complete on the first volley, which meant the Americans could put an entire battalion’s fire onto a road junction with no warning at all, and combine it with the time on target technique the Third Army used heavily, in which a dozen batteries at different ranges each fire at their own calculated moment, so that every shell in the

mission arrives in the same few seconds. There is no first round to take cover from. The first thing the target knows is all of it at once in the air above him. It removed the observer. The fuse did not care whether anyone could see the target. It measured its own height above whatever was underneath it.

Fog, snow, darkness, smoke, none of it mattered to a radio. It removed the terrain. Tree bursts needed trees. This needed nothing. Over a bare hillside in the snow, over a frozen field, over a crossroads, the burst came at the same height it came at everywhere else. And it removed the hole. Go back to the grenadier.

He is in a scrape in frozen ground in a formation that has been moving for days in an attack. He has no overhead cover because overhead cover means logs and cut timber and hours of work and you do not build it during an advance. Everything he has been taught to do is the correct response to a shell that bursts on the ground.

The shell bursts 80 ft over his head instead, and the fragments arrive as a cone driven downward. And the hole he is lying in is now a container that is catching them. There is no answer available to him. He cannot dig deeper. The ground is frozen and there is no time. He cannot run because moving in the open under air burst is worse.

He cannot spread out enough to matter because the pattern covers ground rather than points. He cannot shoot back at what is doing it because it is 4 mi away and he has never seen it and he cannot even take the small comfort of understanding it because everything he knows says shells do not do this over open snow. Around Baston on Christmas Day when the Germans made their heaviest attempt on the perimeter and came in across open white ground in daylight, American artillery firing this ammunition caught infantry in the open with nothing between them

and the sky. The same thing happened at road junctions and assembly areas across the salient through the last week of the month at night and in weather on targets nobody had eyes on. The verdict comes from three directions and they agree. The first is the men underneath it. German prisoners taken during and after the offensive were questioned as prisoners always were.

And what they described was an American shell that burst in the air every time, which they could not account for and had no counter to, and which they discussed among themselves in terms of a new weapon rather than a new technique. The belief that the Americans had somehow perfected the automatic tree burst was general, and it followed them into the interrogation tents.

The second is Patton. He wrote to Major General Leaven Campbell, the chief of ordinance, about the effect of the new ammunition on the fighting in front of Third Army, and he called it the new shell with the funny fuse. And he said plainly that it was devastating, and that when every army had it, war would have to be conducted by some different method.

This is a man not given to enthusiasm about other people’s equipment. The third is the arithmetic done afterward. American evaluation of the two fuses against troops in the open found the proximity round several times more effective per shell than the ordinary point detonating round and against dugin troops without overhead cover the gap was wider still the same weight of shells the same guns the same crews and a different small object screwed into the nose now the honest part because it belongs in the story rather than buried after it there

is no captured German document in which a vermach artillery officer names the American proximity fuse and sets down what it did to his battalion. The verdict from the German side is American interrogators writing down what frightened prisoners told them and American afteraction reports and post-war assessment.

It is good evidence and it is consistent evidence and it is not the same thing as a German staff study and anyone who tells you otherwise is selling you something. Nor did the Fuse win the Battle of the Bulge, and the claim gets made too loosely. The German offensive was beaten by a long list of things, and most of them were men.

It was beaten by engineers blowing bridges in front of armored columns with minutes to spare. By the 101st Airborne, and the armor and artillery with them, holding a road hub, they were surrounded in by Third Army pivoting north in weather that should have made it impossible. By St. Vith and the Elsenborn Ridge where American infantry and gunners simply did not move and it was beaten by German fuel or the absence of it because the whole plan required capturing American stocks and the plan did not get them.

The sky cleared on the 23rd and the fighter bombers came out and that mattered enormously. The proximity fuse arrived in the middle of that as an accelerant. >> [snorts] >> It made American artillery, which was already the best organized in the world in its fire direction and its ability to mass many battalions onto one target, roughly several times more lethal per round against exactly the kind of target the Germans were obliged to present, which was infantry moving in the open in daylight and darkness against prepared positions on a timetable. It arrived at

the hour when the weather had taken away every other American advantage except the guns. The other honest note is what it costs to keep secret. And this cuts the other way. Every month the fuse stayed locked up over land. American infantry were attacking pill boxes and hedge and forest lines without it.

The security decision was probably right. It was not free. So go back one last time to the hole in the frozen pine east of Baston. He began that week with a certainty that had been true since 1940. That fog protects. That a hole protects. that a shell which cannot see you and cannot land on you cannot kill you.

He ended it lying under a sky that had opened without any of the warning the last four years had taught him to expect. Holding a rifle aimed at nothing in a shelter that had turned into a container for other men’s fragments, telling himself the only story that fitted, which was that the Americans had learned to burst every shell in the treetops.

There were no trees over that field. There was a small radio in the nose of a shell and a battery made of glass that only came alive after the gun fired it and a name chosen so that if he ever heard it, he would think it meant something else. He never did hear it. That is rather the point of the name. If your father or your grandfather served in a field artillery battalion in the Ardens, in the 101st at Baston, or anywhere on that line in the winter of 1944, leave his name and his unit in the comments because those names are the record that lasts. And if you worked on

the fuses themselves at Crosley or Sylvania or any of the plants that turned them out by the million or if you ever cut a time fuse by hand on a gunline and know exactly how much better this was, tell us. The people who were there are getting fewer every year.

German Gunners Couldn’t Explain Why American Shells Were Bursting in the Treetops

In the last week of December 1944, in a stand of frozen pine east of Baston, a German grenadier lay in a hole he had cut into ground so hard the entrenching tools rang on it. And he understood exactly what was keeping him alive. He understood the fog. It had sat on the Ardens for a week, a low gray ceiling that had grounded every Allied aircraft in Northwest Europe.

And for a soldier who had spent the autumn being hunted from the air by fighter bombers he could hear but never see in time. That ceiling was the finest thing the winter had given him. He understood the hole. A hole in the ground is one of the oldest solved problems in war. A shell that lands on the earth throws its fragments up and out in a low flat fan.

And a man below the level of that fan is not in the fan. He had been taught the arithmetic of it in training. And then he had been taught it again by four years of surviving. And he trusted it the way a man trusts a floor. So when the American guns opened, he did what he had always done, which was to get low and wait for it to be over.

The shells did not land. That is the part he could not put anywhere. They came in with the sound he knew, and then they stopped 20 ft up, 50 ft up, above the pines, and above his hole. And they burst there in the air over open ground where there was nothing to burst against. And the fragments came down, not out, down, into the hole, onto the men beside him, into the one place on the whole battlefield that had always been safe.

Every man on that ridge came to the same conclusion because it was the only conclusion available. The Americans had found some way to make every single shell burst in the treetops. everyone on the first round without ranging in fog in the dark overground with no trees on it at all. They were wrong.

What was above them was not a trick of gunnery. And it was not a new kind of tree burst. It was a radio and a battery made of glass and five vacuum tubes the size of a man’s thumb packed into the nose of an artillery shell and sold to the world under a name that was a deliberate lie. This is the story of the proximity fuse.

of the two years it spent locked up under a security order that forbade the army from firing it over land and of the word that came over the wire in December 1944 that unlocked it. By the end of this you will know that word. You will know the phrase General George Patton put in a letter to the chief of ordinance about what it did to the Germans in front of him.

and you will know what the prisoners taken in the Ardens told their American interrogators they believed was happening to them which is the closest thing we have to a verdict from the men who were underneath it. Start with the ground because the ground is why the fuse mattered here and not somewhere else.

The Ardens in December 1944 was a country of steep wooded ridges, narrow roads and deep snow held in a weather system that behaved like a weapon. Fog every morning, low cloud that did not lift. temperatures that froze the grease in machine guns and the fuel in trucks. From the 16th of December, when the offensive opened until the sky finally broke on the 23rd, Allied air power was effectively absent from the battlefield and every German commander in the operation had planned on exactly that.

The weather was not a piece of luck. It was a scheduled component of the plan. What that left was artillery. In fog and darkness, the American observer could not see the target. The fighter bomber could not fly, and the tank could not identify what it was shooting at. The howitzer could still fire because a howitzer does not need to see anything.

It needs a map, a survey, and a set of numbers. The trouble was what the shell did when it got there. Understand that the German soldier’s confidence was not stupidity, and it was not propaganda. It was arithmetic and it had been right every time he tested it. A 105 mm shell with an ordinary point detonating fuse strikes the earth and detonates at ground level.

And a large part of its energy goes into the earth and a large part of its fragmentation goes upward at an angle. Against men standing in the open, it is murderous. Against men lying flat, it is much less so. Against men in a hole, it is close to useless, unless the round lands almost on top of them. Soldiers on every front had learned this and dug accordingly.

And the deeper the hole, the more the arithmetic favored the man in it. There was only one answer to a hole. And every artillery officer in every army knew what it was. You do not try to hit the hole. You burst the shell in the air above it. So the fragments come down through the opening at the top.

The Americans had a way of doing that, and the way was bad. It was called a time fuse, and it worked exactly as it sounds. Before firing, a crewman set a mechanical ring on the nose of the shell to a running time. So many seconds, so many fractions of a second, and the fuse burned or ran down and detonated the shell when the time expired.

To put that burst at the right height over the right ground, you needed the range solved precisely. The muzzle velocity of that particular worn barrel accounted for the air temperature and the powder temperature and the wind aloft. And then you needed a forward observer who could see the bursts and correct them, walking them down or up until the height was right.

Registration rounds first, then correction, then fire for effect. Every part of that was expensive. It took time, which in a moving fight is the thing nobody has. It gave away the intention because the ranging rounds told the enemy that something larger was coming and roughly where. It burned ammunition on shells that were not yet hitting anything, and it depended entirely on an observer with eyes on the target, which in an Arden’s fog at 3:00 in the afternoon in a pine forest meant it depended on nothing.

Even done perfectly, it was inconsistent. Fuses varied, barrels varied. A battery firing a time fuse mission scattered its bursts through a range of heights. Some too high to be worth much, some low enough to hit the ground and be wasted, and only a portion in the band where they did what they were meant to do.

There was a second method, and it was the reason the German assumption about treetops existed at all. In heavily wooded country, you could fire ordinary point detonating rounds into the crowns of the trees and let the trunks and branches do the fusing for you. The shell hit a tree 50 ft up, burst there, and rained fragments and splintered timber onto everything below.

The Americans and the Germans both used it and both feared it. And in the Herkin forest that autumn, it had done frightful work in both directions. That is why when the shells started bursting overhead in the Arden, the German soldier reached for the explanation he had. Tree bursts. The Americans have got very good at tree bursts.

The explanation collapsed the moment the same thing happened over a snowfield with nothing standing on it. The thing in the nose of those shells had begun as an idea nearly everybody in the business considered impossible, and it had come to the Americans partly as a gift. In 1940, when Britain was alone and expected to be invaded, a delegation under Sir Henry Tizzard crossed the Atlantic carrying the best of British military science in a black metal box and handed it to a country that was not yet in the war.

Most of the attention goes to the cavity magnetron, which made centimetric radar possible. In the same package was British work on a fuse that would sense its own approach to a target and fire itself. The idea was old and the engineering was thought to be beyond reach. Put a small radio transmitter and receiver in the nose of a shell.

Have it broadcast continuously and listen for its own signal coming back off whatever it is approaching. As the shell closes, the returning signal shifts and strengthens in a way the circuit can recognize. And at the right moment, the circuit closes a switch and detonates the round. On a laboratory bench with unlimited time, this is difficult.

In an artillery shell, it is close to absurd. And here is why. When a 5-in naval gun fires, everything inside the shell is subjected to an acceleration in the region of 20,000 times gravity. A glass vacuum tube weighing a few grams briefly weighs the equivalent of a sack of cement. Then once clear of the muzzle, the shell spins on its axis at hundreds of revolutions per second to keep it stable, which throws every loose component outward with enormous force.

The device had to survive both, then work reliably seconds later, having sat in a magazine or a shell dump for a year beforehand. The work went to section T under the National Defense Research Committee and then to the Applied Physics Laboratory at John’s Hopkins under a physicist named Merurl Touve. What his people did was solve the problems one at a time in ways that sound like improvisation and were not.

The tubes came down from the hearing aid industry which already made the smallest vacuum tubes in the world and then were rebuilt with heavier internal supports and shortened elements until they could take the setback shock. The battery was the elegant one. An ordinary battery sitting in storage for months goes flat.

And no army wants ammunition whose fuses have quietly died in the crate. So they built a battery with no electrolyte in it. The acid sat sealed in a small glass ampule inside the fuse, chemically separate and indefinitely stable. The shock of firing shattered the ampule and the spin of the shell flung the liquid outward into the plates and the battery came alive somewhere in the first fraction of a second of flight.

The fuse was dead in the box and dead in the breach and only became a live electronic device once the gun had already fired it. Then they named it. Somebody decided the security of the thing would be helped by a name that told a listener the wrong story. And so it was called the VT Fuse for variable time. Anybody who overheard the term would assume it was a refinement of the time fused the world already knew about.

It was nothing of the kind. The deception was built into the vocabulary from the first day. The scale of what followed is not widely appreciated. The program ran to roughly a billion dollars of wartime money and something in the order of 22 million fuses made by firms including Cley, Sylvania, General Electric, Eastman, Kodak, and RCA, factories that had been making radios and camera parts and hearing aids and were now turning out a precision electronic assembly designed to be destroyed on first use.

Vanavar Bush, who ran American wartime science, put it alongside radar and the atomic bomb in the front rank of what the laboratories had delivered. And for two years, the army in Europe was forbidden to fire it at the ground. The reason was sound, and everybody hated it. A fuse that goes off in the air destroys itself.

A fuse that fails and a proportion always fail falls to Earth substantially intact. If that happened over water, the fuse went to the bottom and was gone. If it happened over enemy held land, a German technician would in due course be holding an American radio proximity fuse in his hands. And the Germans had their own proximity fuse research running and lacked only the manufacturing solutions the Americans had spent 2 years finding.

The nightmare was specific and it was not paranoid. Allied bomber streams were flying daily over German anti-aircraft belts. A German 88 firing shells that burst automatically at the correct height inside a bomber formation would have raised the cost of the air campaign to something unbearable. So the fuse went to sea first where dud sank.

On the 5th of January 1943, the cruiser USS Helena in the Solomons brought down a Japanese aircraft with a proximity fused 5-in round, the first kill of its kind. Naval anti-aircraft gunnery was transformed inside a year. Then it went to England. In the summer of 1944, the V1 flying bombs came over in numbers, and the gun belt on the South Coast was firing at a small, fast machine, flying a straight line at a constant height, which is the perfect customer for a fuse that only has to be close.

Combined with SCR584 gun laying radar and the M9 electrical director, the results at the end of that campaign were extraordinary, with the great majority of the bombs entering the belt destroyed before they crossed it. Duds fell in the channel and in English fields the army controlled over the front line in France and Belgium it stayed locked.

Field artillery officers knew it existed. They knew what it would do to infantry in the open. They were not allowed to have it. The Ardens broke the lock. Accounts differ slightly on the precise date the authorization took effect and that is worth saying rather than hiding because you will see different days given in different books.

What is not in dispute is that in the second half of December 1944, with two German armies driving west through the American center and the weather keeping the Allied air forces on the ground, the restriction on ground use in Europe was lifted and the artillery battalions were told they could fire it.

The word that went out to identify it was pose it. That was the code word and it went onto the fire missions and into the radio traffic. And to a battery executive who had spent months hearing rumors, “Pose it meant one thing. Fire it. Do not range it. Do not adjust the height of burst. Do not wait for the observer to walk it down.

Send it and it will burst where it needs to burst.” What made it so violent in that particular fight was the combination of things it removed. It removed the ranging. A time fuse mission announced itself. A proximityfused mission arrived complete on the first volley, which meant the Americans could put an entire battalion’s fire onto a road junction with no warning at all, and combine it with the time on target technique the Third Army used heavily, in which a dozen batteries at different ranges each fire at their own calculated moment, so that every shell in the

mission arrives in the same few seconds. There is no first round to take cover from. The first thing the target knows is all of it at once in the air above him. It removed the observer. The fuse did not care whether anyone could see the target. It measured its own height above whatever was underneath it.

Fog, snow, darkness, smoke, none of it mattered to a radio. It removed the terrain. Tree bursts needed trees. This needed nothing. Over a bare hillside in the snow, over a frozen field, over a crossroads, the burst came at the same height it came at everywhere else. And it removed the hole. Go back to the grenadier.

He is in a scrape in frozen ground in a formation that has been moving for days in an attack. He has no overhead cover because overhead cover means logs and cut timber and hours of work and you do not build it during an advance. Everything he has been taught to do is the correct response to a shell that bursts on the ground.

The shell bursts 80 ft over his head instead, and the fragments arrive as a cone driven downward. And the hole he is lying in is now a container that is catching them. There is no answer available to him. He cannot dig deeper. The ground is frozen and there is no time. He cannot run because moving in the open under air burst is worse.

He cannot spread out enough to matter because the pattern covers ground rather than points. He cannot shoot back at what is doing it because it is 4 mi away and he has never seen it and he cannot even take the small comfort of understanding it because everything he knows says shells do not do this over open snow. Around Baston on Christmas Day when the Germans made their heaviest attempt on the perimeter and came in across open white ground in daylight, American artillery firing this ammunition caught infantry in the open with nothing between them

and the sky. The same thing happened at road junctions and assembly areas across the salient through the last week of the month at night and in weather on targets nobody had eyes on. The verdict comes from three directions and they agree. The first is the men underneath it. German prisoners taken during and after the offensive were questioned as prisoners always were.

And what they described was an American shell that burst in the air every time, which they could not account for and had no counter to, and which they discussed among themselves in terms of a new weapon rather than a new technique. The belief that the Americans had somehow perfected the automatic tree burst was general, and it followed them into the interrogation tents.

The second is Patton. He wrote to Major General Leaven Campbell, the chief of ordinance, about the effect of the new ammunition on the fighting in front of Third Army, and he called it the new shell with the funny fuse. And he said plainly that it was devastating, and that when every army had it, war would have to be conducted by some different method.

This is a man not given to enthusiasm about other people’s equipment. The third is the arithmetic done afterward. American evaluation of the two fuses against troops in the open found the proximity round several times more effective per shell than the ordinary point detonating round and against dugin troops without overhead cover the gap was wider still the same weight of shells the same guns the same crews and a different small object screwed into the nose now the honest part because it belongs in the story rather than buried after it there

is no captured German document in which a vermach artillery officer names the American proximity fuse and sets down what it did to his battalion. The verdict from the German side is American interrogators writing down what frightened prisoners told them and American afteraction reports and post-war assessment.

It is good evidence and it is consistent evidence and it is not the same thing as a German staff study and anyone who tells you otherwise is selling you something. Nor did the Fuse win the Battle of the Bulge, and the claim gets made too loosely. The German offensive was beaten by a long list of things, and most of them were men.

It was beaten by engineers blowing bridges in front of armored columns with minutes to spare. By the 101st Airborne, and the armor and artillery with them, holding a road hub, they were surrounded in by Third Army pivoting north in weather that should have made it impossible. By St. Vith and the Elsenborn Ridge where American infantry and gunners simply did not move and it was beaten by German fuel or the absence of it because the whole plan required capturing American stocks and the plan did not get them.

The sky cleared on the 23rd and the fighter bombers came out and that mattered enormously. The proximity fuse arrived in the middle of that as an accelerant. >> [snorts] >> It made American artillery, which was already the best organized in the world in its fire direction and its ability to mass many battalions onto one target, roughly several times more lethal per round against exactly the kind of target the Germans were obliged to present, which was infantry moving in the open in daylight and darkness against prepared positions on a timetable. It arrived at

the hour when the weather had taken away every other American advantage except the guns. The other honest note is what it costs to keep secret. And this cuts the other way. Every month the fuse stayed locked up over land. American infantry were attacking pill boxes and hedge and forest lines without it.

The security decision was probably right. It was not free. So go back one last time to the hole in the frozen pine east of Baston. He began that week with a certainty that had been true since 1940. That fog protects. That a hole protects. that a shell which cannot see you and cannot land on you cannot kill you.

He ended it lying under a sky that had opened without any of the warning the last four years had taught him to expect. Holding a rifle aimed at nothing in a shelter that had turned into a container for other men’s fragments, telling himself the only story that fitted, which was that the Americans had learned to burst every shell in the treetops.

There were no trees over that field. There was a small radio in the nose of a shell and a battery made of glass that only came alive after the gun fired it and a name chosen so that if he ever heard it, he would think it meant something else. He never did hear it. That is rather the point of the name. If your father or your grandfather served in a field artillery battalion in the Ardens, in the 101st at Baston, or anywhere on that line in the winter of 1944, leave his name and his unit in the comments because those names are the record that lasts. And if you worked on

the fuses themselves at Crosley or Sylvania or any of the plants that turned them out by the million or if you ever cut a time fuse by hand on a gunline and know exactly how much better this was, tell us. The people who were there are getting fewer every year.