Hitting the Books: How one of our first 'smart' weapons helped stop the Nazis

This crucial WWII invention had nothing to do with nukes.

At the outset of World War II, you’d have a better chance of finding a needle in a haystack with a camel stuck in its eye than you did shooting down an enemy aircraft in your first dozen or so shots. This is because anti-aircraft shells at the time used manual fuses that had to be dialed in for specific lengths of time to delay their explosion. The idea was that you’d estimate where the targeted plane would be in, say five seconds, based on its currently flight path, then time the shell for that length, fire the shell at the plane and hope that the timing and location were close enough that shrapnel from the exploding shell hits the plane. If your calculations were off by even a hair, the shell would miss by thousands of feet. And if shooting down piloted aircraft was this hard, intercepting Germany’s terrifyingly fast V1 and V2 rockets required far more luck than skill. But that’s exactly what the team at Section T set out to do.

In 12 Seconds of Silence: How a Team of Inventors, Tinkerers, and Spies Took Down a Nazi Superweapon, author Jamie Holmes recounts the incredible story behind the advent of the proximity fuse, an innocuous device that leveraged newfangled radar technology to tell anti-aircraft shells when they should detonate for maximum effect. But this was no simple bit of R&D. The man tasked with leading the development, American geophysicist Merle Tuve, had to build the entire research effort from the ground up — facilities, personnel, logistics, testing, the whole shebang. And all while the Nazi war machine ran roughshod over the European continent. In the excerpt below, we join the Section T team on a pier in Norfolk, Virginia as they demonstrate the proximity fuse to Navy brass against moving targets in a bid for the military to adopt the technology.

12 Seconds of Silence cover
Houghton Mifflin Harcourt

Excerpted from 12 Seconds of Silence: How a Team of Inventors, Tinkerers, and Spies Took Down a Nazi Superweapon by Jamie Holmes. Used by permission of Houghton Mifflin Harcourt.

From the deck of the USS Lexington, on May 8, 1942, a barrage of deafening shots flung dozens of five-inch rounds into the clear sky. They pockmarked the air with black plumes, peppering the vista with inkblots of exploding shrapnel.

In the Coral Sea, off Australia’s northeastern coast, the 888-foot Navy aircraft carrier was under heavy assault by eighteen fighters and thirty-six torpedo and dive-bombers. The Lexington and a second carrier, USS Yorktown, formed the heart of an Allied mission to stop the Japanese from invading and occupying Port Moresby, New Guinea, a strategic foothold right off Australia’s doorstep.

Frederick Sherman, the Lexington’s captain, steered sharply at high speed to dodge the falling bombs, jolting his men under the deck and causing the huge vessel to roll, sway, and moan. Bullets from Japanese gunners in the planes struck a violent staccato beat on the metal hull and echoed through the ship’s belly. Axis bombs narrowly missed the carrier deck and exploded under the water, unleashing pressurized tremors that popped the American sailors’ ears.

The ship had never faced a raid of such intensity.

On the port side, a set of three five-inch antiaircraft guns blazed away stubbornly at the bombers. Jesse Rutherford Jr., a nineteen-year-old from Kansas, hoisted the fifty-four-pound rounds from the ammunition locker at his feet. Like a link in a bucket brigade, he handed them to the “primary loader,” a fellow Marine standing at the breech of the twelve-foot, two-ton monster called gun no. 10. Rutherford was among a small contingent of Marines manning the guns. Since six a.m., the captain had them at the ready wearing “flash gear” — heavy, fire-resistant clothing that included a protective hood and gloves. The Marines had waited five hours in the baking heat before the Japanese attack was spotted.

Most of the Lexington’s planes were far away, executing their own raid on Japanese carriers. With only a handful of Allied planes remaining, the Japanese easily reached the Lexington, prompting ack-ack fire from its gunners. But the small-caliber machine guns and five-inch cannons did not deter the pilots, who flew without hesitation, largely untouched, through the porous flak.

After the first minute of the assault, it became difficult for the men   to discern the exact order of events or where the bombs and bullets were coming from. Usually, four Mk 19 “gun directors” with telescopic lenses would have tracked incoming aircraft, determined the height, range, and bearing of enemy planes, and fed coordinates to the gun mounts. But the attack was so chaotic that gunners were given “local control” over where to shoot and had to select their own ammunition.

Inside the shells, time fuses adjusted by twisting a metal ring were all preset. The scheme saved men from having to calibrate them during the heat of battle, but it was wildly inflexible. As bombs fell, gunners tried   to determine the flight paths of approaching raiders, and then figure out where those flight paths might meet in midair with a shell that blew up at 2.2, 3, or 5.2 seconds after being fired. The Lexington’s antiaircraft guns could not protect the ship.

Within minutes, around eleven twenty a.m., it was hit by a series of torpedoes, producing explosions so violent that they froze the elevators and fractured the aviation-fuel storage tanks, which began to leak gas and poisonous vapors. Beneath the deck, repair teams quickly dispatched crews to plug the holes in the hull, and starboard compartments were “counter-flooded.”

On the bridge, Captain Sherman craved a cigarette, but the fumes made smoking too dangerous. In the distance, he saw that the faster, more agile carrier Yorktown was also being ambushed. Naval tactics dictated that the ships in the Allied battle group (which included cruisers and destroyers) should form a strategic ring to maximize their antiaircraft guns. But the formation had broken. A bomb pierced the hull and exploded in the admiral’s and chief of staff’s living quarters, enflaming furniture and distorting the lip of the deck.

The Marines at guns 2, 4, and 6 suffered a direct hit. Marine Corps captain Ralph Houser, their commanding officer, discovered the gruesome scene. Like victims at Pompeii, the charred bodies were frozen at their gun positions. Wounded men moaned and bled on the gnarled deck. Medics applied battle dressings and tannic jelly to their burns, and administered morphine.

A jagged hole punctured the deck beside gun no. 2. The explosion splintered a storage locker of five-inch shells, scattering them. Swelling with heat, rounds slipped from their brass cases and spilled firing powder, which ignited in tails of flame and let out angry hisses.

Two Japanese planes sprayed the deck with machine-gun fire, wounding three men working gun no. 10 and ending the life of another. Rutherford was shot several times but refused to stop lifting the heavy shells, one by one, for loading. Bombs hit the water and threw up towering walls of ocean, obscuring the ship’s profile and soaking the gunners still desperately trying to save the ship.

The attack lasted only twenty-three minutes. When it was over, the Lexington’s gunners had shot down only six of the fifty-four Japanese aircraft in the assault group.

It was now just a matter of time. At 12:47 p.m., the leaking aviation fuel blew up, taking out the damage control station. Two hours later, an explosion knocked an elevator through the flight deck. At 3:25, another blast took out the water pressure in the hangar. At 5:07, Captain Sherman gave the order to abandon ship.

Floating helplessly, the crew were unable to get far away from the sinking hull as the vortex of churning currents pulled them closer, like a magnet. That night, over twenty-seven hundred men of the almost three thousand aboard were safely rescued by Allied ships.

The loss of the Lexington reinforced the lesson of the Prince of Wales and the Repulse. Ships could not defend themselves without air cover. “Air offense is definitely superior to the defense,” the incident report dryly concluded.

The Battle of the Coral Sea marked the first time in history that enemy aircraft carriers waged a fight against each other. It was the first battle in history in which neither side’s ships ever saw or fired directly on the others.

Naval airpower had come of age.

It was a tactical loss but a strategic victory. Japan failed to take Port Moresby, and a Japanese carrier was sunk. The contest also marked a turn for the Navy, which was preparing to go on the offensive and, in 1943, hoped to claw back Japanese gains in the Pacific and take the war to the nation’s island citadel itself.

Japanese resistance would be deadly and savage.

After the Lexington sank to the ocean floor, the USS Yorktown limped to Pearl Harbor, where the vessel underwent a frantic repair job to return it to action.

Weeks later, the Yorktown sunk too.


Sailors met the scientists at the waterfront.

Dick Roberts was impressed by the Navy work party, which swiftly loaded the radios, binoculars, and batches of secret fuses.

August 10, 1942, was less than two years since Roberts initiated the fuse project, with some swagger, on Merle’s request, by firing a pistol at a vacuum tube in a bunker underneath a particle accelerator. He could not have guessed where that journey would lead. Now in front of the physicist, on a pier in Norfolk, Virginia, was a six-hundred-ten-foot Navy cruiser known as the USS Cleveland.

An imposing metal giant — a freshly commissioned ship — the Cleveland displaced some eleven thousand tons of water and carried a thousand men. At the stern was a crane used for retrieving four scouting seaplanes. In its center were stacks of circular towers, curved platforms, and boxy compartments. The ship’s core gave the impression of a small mountaintop favela made of iron, where generations of inhabitants added their own ferrous modules as space allowed.

The vessel was heavily armed. Four turrets and twelve guns used for land bombardment dotted the bow and stern. Behind them, encircling a rounded bridge, slanted masts, and dual smokestacks, were twelve five-inch guns in six turrets. The Navy was well aware by now that the guns weren’t enough, and had been busy cluttering the decks of cruisers like the Cleveland with dozens of smaller twenty- and forty-millimeter guns. The Cleveland itself had thirty-two of them. The ship was not designed to handle the weight of the extra guns and their aiming devices, and the boat — like others in its class — had grown increasingly unstable as it overflowed with more and more guns that were fitted like porcupine quills to the deck.

Roberts climbed the gangplank onto the massive carrier. With him was Section T’s “Mac” McAlister, from the Smithsonian Institution, and Herb Trotter Jr., a square-jawed physicist from Washington and Lee who looked more like an amateur boxer than a scientist. Lieutenant Deak Parsons was overseeing things.

As the Cleveland set off into Chesapeake Bay, the steam turbine engines propelled the sailors, researchers, film cameras, and precious fuses past the York and Rappahannock Rivers to Tangier Island, seventy miles north. The cruiser stopped at the widest stretch of the estuary, and made anchor for the night.

The ship’s insides were as alien to Roberts as its cluttered skin. Below deck, he encountered a maze of control rooms, berths, narrow passages, repair shops, ammunition rooms, supply rooms for spare parts, diving gear, and “chemical defense material.” The Cleveland was a tiny city with a post office, bakery, metalworking shop, optical shop, and even a room for “potato stowage.”

Roberts would not be sleeping in the “guest cabin” with its matching bath. He was bunked along a corridor and would have a more plebian naval experience. The ship was on a “shakedown” cruise to test its performance and ready the crew, and the sailors were kept busy with unexpected drills. The boatswain would blow a high-pitched pipe, and sailors would rush to their battle stations, prepare to abandon ship, or respond to “fires,” “collisions,” and “damage reports.” The physicist was sound asleep the next day, at five a.m., when he was suddenly jolted awake  while “half the crew ran over” his bunk for a surprise drill.

Tangier Island warmed slowly in the August heat, and as the sun climbed in the sky, Roberts, Parsons, and the other Section T men gathered on deck. Today’s test was against moving targets.

Small drones — remote-controlled planes about the size of an albatross, used for gunnery practice — were notoriously difficult to shoot down. The tiny aircraft were so tough to knock from the sky that even though Parsons had requested six target planes for the trial, the Navy drone technicians opted to bring only four. In their experience, ambitious gunnery officers usually asked for more target planes than needed. Their drones were rarely damaged beyond repair. The Navy photographic crew assigned to document the trials told Roberts that they had never once seen a drone shot down.

The waterway was cleared. The remote-control drone pilot steadied his hands. A radar, range finder, and mechanical “predictor” would help to aim the guns. Section T fuses, fitted into five-inch shells, were duly  loaded. As the first drone left the deck, the Cleveland ’s gunnery crew was primed and ready for action.

Each pair of five-inch guns on the ship protruded from an enclosed mount that resembled a squat tank with no treads. A standard gun crew consisted of twenty-six men, but twenty-seven were required for firing practice. The mount needed “powder men” to handle the powder casings, two “projectile and rammer men” to prepare rounds for firing, and two “hot case” men to catch ejected casings. “Trainers,” “sight setters,” and “pointers” were normally at the ready to aim the guns manually using optical lenses. And there would usually be a fuse setter, who was not needed that day and whose job, should Section T succeed, would no longer exist.

Under the guns, in ammunition handling rooms, thirteen of the men operated hoists and supplied powder cases and projectiles to the guns. Both rooms in this miniature, two-story arrangement had managers pre- pared to supervise the frenetic symphony of churning metal belts, valves, shells, and deafening explosions.

The first drone promptly crashed into the water, defective.

Roberts peered through binoculars at the second drone as it began a run toward the ship from three thousand yards away. The five-inch guns unleashed eighty rounds, and within seconds three shells detonated and struck the drone on the right side. It burst into flames and then spiraled into the drink. The third drone, launched off the starboard side, fell after four rounds. Over forty-five hundred feet away, a shell with a smart fuse sliced it with shrapnel and knocked it into Chesapeake Bay.

Parsons requested another target plane. But the drone operators didn’t have the last one ready. According to Roberts, Parsons was irate. He’d asked them for six drones, and they had refused. Why wasn’t the fourth drone ready, at least?

“You’ve wrecked two of my drones,” a handler said. “That’s very expensive.”

When the final plane was ready, over an hour later, its pilot simulated a low-altitude bombing run. The lower height didn’t make a difference. Eight shots and it was gone. Eighty rounds for a single target? Eight? Four? By any measure, the results of the drone trials were spectacular. The Cleveland’s captain came down to congratulate Parsons and the Section T men. As the physicists boarded a small launch to return to shore, he ordered life preservers brought for them. To prevent the hundreds of sailors aboard from spreading news of the test — of the wondrous accuracy of some new secret weapon — the Navy canceled their shore leave.

Tuve’s boss was elated. “Three runs, three hits, and no errors,” Bush wrote Conant, in a telegram. The fuse did exactly what it was supposed to.

Now they just had to put it to war.