What America Did With Japan's Secret Weapons After the War

[00:00:00]Late August 1945, the destroyer USS Blue is cutting through open water 500 miles northeast of Tokyo. The war ended 12 days ago. And now somewhere ahead, a Japanese submarine is surfacing. Not to fight, to surrender. But before the black flag goes up on its conning tower, something strange is happening on deck. The Japanese crew is dragging aircraft out of a sealed hanger, three folding wing sea planes, and shoving them over the side one by one. They fire every torpedo without arming them. They dump code books. They destroy charts. By the time American sailors climb aboard on August 27th, the hanger is empty. The crew of the Blue doesn't understand what they're looking at. The submarine beneath their boots is longer than their own destroyer. It has a sealed aircraft hanger running along its deck, launch rails, a compressed air catapult on the bow. No American intelligence agency knew this vessel existed until its crew came to the surface and gave themselves up. And that was just the first week. In the weeks and months that followed, teams of American engineers, intelligence officers, and test pilots spread across defeated Japan into shipyards, weapons factories, airfields, and laboratories. Every door they opened revealed something that wasn't in any briefing. Torpedoes running on technology, the U Navy said, couldn't work. paper balloons that had already crossed the Pacific and landed on American soil, jet aircraft sitting half-finished in bombed out factories, and the largest submarine ever built, designed to strike the American mainland without ever being detected. Each discovery told the same story. The enemy that America had just defeated was more dangerous than anyone realized.

[00:02:04]This is what they found. The American flag went up over I400 at 5 in the morning on August 31st, 1945.

[00:02:15]Commander Hyram Cassidy, a veteran submariner who had captained two boats during the war, took command with a prize crew of four officers and 40 men.

[00:02:26]What Cassidy found was unlike anything in the US Navy's inventory. I400 stretched 400 ft. That made her the largest submarine in the world, a record she would hold for the next 20 years until America's own nuclear ballistic missile submarines surpassed her in the 1960s.

[00:02:46]Her pressure hull had a figure8 cross-section, an engineering solution no American designer had attempted, built to support the weight of a waterproof aircraft hanger that ran 102 feet along the upper deck. Inside that hanger, before the crew emptied it, sat three Ichi M6 Acarin torpedo bombers.

[00:03:08]Their wings folded, their floats detached, designed to be assembled, launched by catapult, and airborne in minutes. Then the submarine would dive and disappear. The concept had started with Admiral Yamamoto shortly after Pearl Harbor. He wanted 18 of these boats. An underwater fleet carrying aircraft that could strike New York, Washington, or the Panama Canal and vanish before anyone knew they were there. Each submarine carried enough fuel to circle the globe one and a half times without refueling. No port calls, no supply lines, just a submarine, three bombers, and the entire coastline of the United States. But Yamamoto was gone by April 1943.

[00:03:58]And after his death, the program shrank.

[00:04:02]18 became 9. 9 became five. Five became three. Only I400 and I 4001 saw service.

[00:04:12]The third boat I 4002 was completed 5 weeks before the war ended. She never left port. The final mission was an air strike on the American anchorage at Ulithy in the Caroline Islands. 10 aircraft from the combined force, some flown by men who would not be coming back, were to hit the fleet at anchor.

[00:04:35]The attack was scheduled. The crews were trained. Then Japan surrendered. The submarines received the order to destroy all weapons on August 22nd, 5 days later. They surfaced and gave themselves up. I400 and I4001 were studied first at Sassibo, Japan through November and December of 1945.

[00:05:00]American engineers crawled over every compartment, photographed every system, cataloged every innovation. They found an anecquic rubber coating on the hull designed to absorb sonar technology the UIS Navy had never seen on a submarine. They found a deossing system to defeat magnetic mines. Air search radar with a range of 50 mi. In January 1946, both submarines were towed across the Pacific to Pearl Harbor for further evaluation.

[00:05:33]For the next several months, engineers continued their work. They learned everything the boats had to teach.

[00:05:41]Then in March 1946, an order came from Washington. The Soviets were demanding access to captured Japanese submarines.

[00:05:51]They're right under wartime agreements.

[00:05:53]The Navy's response was immediate. Sink them. Sink all of them. before Moscow sends an inspection team. On June 4th, 1946, Vice Admiral Alan McCann, commander of Submarine Force Pacific, stood on the bridge of USS Trumpet Fish off the coast of Aahu. Beside him was Commander Lawson Ramage, Medal of Honor recipient, one of the most decorated submariners in Navy history. Three Mark 18 torpedoes hit I400 amid ships. Her stern separated.

[00:06:29]She slid beneath the surface and sank to 2300 ft. Macan watched in silence. 67 years later in 2013, a no AAA research team found her wreckage on the ocean floor. The hanger was still intact, the catapult rail still pointed forward. The largest submarine of the Second World War, resting in darkness, right where the Navy put her, I400 was the first door America opened in defeated Japan.

[00:06:59]It would not be the last. While the Navy was studying submarines at CBO, other teams were moving through Japan's naval arsenals on shore. In the weapon storage facilities and engineering workshops, they found rows of torpedoes unlike anything in the American inventory.

[00:07:19]9 m long, 24 in in diameter, warheads exceeding 1,000 lb, enough to break a heavy cruiser in half with a single hit.

[00:07:30]And the propulsion system, not steam, not compressed air, pure oxygen. The Americans were looking at the type 93 torpedo. They just didn't know yet how much it had cost them. 5 years earlier in 1940, a Japanese source later described by the Office of Naval Intelligence as an individual of impeccable reliability contacted the American Naval Ataché in Tokyo. He provided detailed information about Japan's oxygen-driven torpedo, its range, its speed, its warhead size, all of it far beyond anything the United States or Britain had in service. Oni forwarded the report to the Bureau of Ordinance in Washington. An officer reviewed it. His assessment impractical.

[00:08:23]Using pure oxygen as a torpedo propellant was too dangerous, too unstable. No Navy would attempt it. The Japanese certainly lacked the engineering capacity to solve a problem that American and British designers had already abandoned. The file was closed.

[00:08:41]Two years later, on the night of August 9th, 1942, a Japanese naval force entered the waters off Tsavo Island in the Solomon Islands. The engagement lasted 37 minutes. Four Allied heavy cruisers went down. USS Quincy, USS Vincen, USS Atoria, and HMAS Canbor.

[00:09:04]Over a thousand Allied sailors were lost in a single night. The surviving American commanders reported they had been struck by mines or by torpedoes from an undetected submarine. No one believed a surface launch torpedo could reach them at that distance. No one believed a torpedo could run that far without leaving a visible wake. They were wrong on both counts. The Type 93 had a range of 40,000 m at 36 knots, more than double any American torpedo.

[00:09:37]Its oxygen propulsion left almost no wake, a faint shimmer on the surface that was invisible at night. Japanese destroyer captains were firing from distances that American doctrine considered safe. Throughout the war in the Pacific, the Type 93 and its variants sank seven American heavy cruisers, nine destroyers, and the aircraft carrier Hornet. More than 3,000 American sailors lost, most of them aboard ships whose commanders believed they were beyond torpedo range. It took until March of 1944, nearly 2 years after Tsavo Island, for American intelligence to confirm the full capabilities of the Type 93 through captured documents and prisoner interrogations.

[00:10:26]The historian Samuel Elliot Morrison gave it its western name after the war, Long Lance. But Long Lance didn't win the war at sea. It couldn't. For every American warship that Long Lance put on the ocean floor, American shipyards launched two more. The United States had superior radar, broken Japanese codes, and an industrial base that Japan could never match. Long Lance was the finest torpedo in the world. It sank warships.

[00:10:58]It did not sink the capacity to build them. After the war, American engineers disassembled captured Type 93 torpedoes in Japanese naval workshops. What they found inside was not some revolutionary breakthrough. It was patience. The oxygen feed system used a first air bottle, compressed air to start the engine, then a gradual transition to pure oxygen as the motor warmed. Every oxygen line was cleaned with a strong alkaline solution. Every pipe bend was eliminated.

[00:11:34]No sharp turns, no trapped pockets where oxygen could concentrate and ignite.

[00:11:40]American and British engineers had tried oxygen propulsion and quit. The Japanese engineers didn't invent a different principle. They simply refused to stop until they solved the one everyone else had given up on. The best torpedo in the world couldn't sink a shipyard. And America had a hundred of them. Long Lance had been hiding in plain sight throughout the entire war. 3,000 sailors paid for a report that sat in a closed file in Washington. But the intelligence teams moving through Japan were about to open another door, one that led to something stranger than anything they had found so far. Because one Japanese weapon had already reached the American mainland, it had already taken American lives on American soil. And for months, no one in the United States could figure out how it got there. On November 4th, 1944, a US Navy patrol recovered a large object floating 68 m off the southern California coast near the Channel Islands. It appeared to be an enormous balloon roughly 33 ft across made of paper. Attached to it was a mechanical device and fragments of an explosive charge. Nobody knew what it was. A month later, on December 6th, witnesses near Thermopoulos, Wyoming, 800 miles deep inside the continental United States, reported a red fireball in the night sky. The next morning, a 15 kg Japanese anti-personnel bomb was recovered from the ground. No Japanese aircraft had been anywhere near the West Coast. No submarine, no ship. The explanation wouldn't come until after the war when American intelligence teams entered production facilities along Japan's eastern coastline and found the answer on the factory floors. After the Dittle raid struck Tokyo in April 1942, Japan wanted to strike back, but by then most of her aircraft carriers were gone.

[00:13:50]She had no longrange bombers. Her submarines had been pushed back from the American coast. There was no conventional way to hit the United States. The solution came from a Japanese meteorologist named Wasaburo Oishi. In the 1920s, Oishi had tracked and documented a powerful high alitude air current flowing from west to east across the Pacific at roughly 30,000 ft.

[00:14:16]What we now call the jetream. American B29 pilots would later encounter this same current at high altitude and struggle against it. But Oishi had studied it 20 years before them.

[00:14:30]Japanese military engineers took his data and built a weapon around it. The Fugo balloon bomb, 33 ft in diameter, made from washi, traditional Japanese handmade paper glued with paste derived from kanyaku, a root vegetable inflated with hydrogen.

[00:14:49]Carrying one anti-personnel bomb and two incendiary devices, an ingenious mechanical system automatically released sandbag ballast to maintain altitude as the balloon crossed the Pacific at 30,000 ft. More than 9,000 of these balloons were launched from the Japanese coast between November 1944 and April 1945.

[00:15:13]School girls were mobilized to assemble them in theaters and factory buildings.

[00:15:17]Roughly 300 reached North America, landing in locations from Alaska to Mexico, scattered across 26 states and into Canada. They were the first intercontinental weapons in history. A decade before the first intercontinental ballistic missile made of paper.

[00:15:39]Washington's response was not military.

[00:15:42]It was silence. The government imposed a complete media blackout. Not a single newspaper. Not a single radio broadcast was permitted to mention the balloons.

[00:15:53]The logic was precise. If Japan received no confirmation that the weapons were arriving, the program would appear to have failed.

[00:16:02]And it worked. Japanese media, receiving no reports of panic or damage from America, was forced to fabricate stories about the balloon's success.

[00:16:13]The military leadership, unable to verify results, questioned the program's value. Meanwhile, in a laboratory in Washington, a geologist at the United States Geological Survey named Clarence Ross sat before a microscope with a handful of sand. The sand had come from the ballast bags recovered with the balloons. Under magnification, the mineral composition and grain structure pointed to a specific origin, coastal sand from beaches near Shiogama on the eastern shore of Honu. Additional samples matched Ichinomia, 40 mi southeast of Tokyo. From grains of sand, the United States identified the launch sites, and B-29s paid them a visit.

[00:17:01]Japan suspended the balloon program in April 1945.

[00:17:06]The official reason was a shortage of raw materials. The Koso trees used to make washi paper had been depleted. But the real reason was simpler. The silence from America had worked. Without confirmation, the program couldn't justify its cost. 9,000 balloons, 300 arrivals, and six lives. On the morning of May 5th, 1945, Reverend Archie Mitchell drove his wife Elsie and five Sunday school students from their church in Bllye, Oregon out to Gearhart Mountain for a Saturday fishing trip.

[00:17:44]Elsie was 26 years old and 5 months pregnant. While Archie parked the car, Elsie and the children walked ahead toward Leonard Creek. One of them called back. They had found something strange in the woods. Archie heard the words. He shouted a warning. Then the explosion.

[00:18:04]Elsie Mitchell, Sherman Shoemaker, age 11. Edward Enen, 13. Jay Gford, 13. Joan Patska, 13. Dick Patska, 14.

[00:18:19]They were the only civilians lost to enemy action on the American mainland during the entire war.

[00:18:26]If stories like this remind you why history still matters, take a second and hit that like button. It's a small thing, but it helps these stories reach the people who need to hear them. Paper balloons across the Pacific. Oxygen torpedoes beneath it. A submarine aircraft carrier that no intelligence agency knew existed.

[00:18:49]Each door the American teams opened in Japan revealed something more unexpected than the last. But in the bombedout aircraft factories and airfield hangers deeper inland, they were about to find something that didn't belong in 1945 at all. On July 7th, 1945, Lieutenant Commander Toyoho Inuzuka of the Imperial Japanese Navy climbed into the cockpit of a small stubby aircraft at a test airfield in Japan. The aircraft was the J8M Shusui, Japan's version of the German MI163 KT, a rocket powered interceptor designed for one purpose, to climb straight up to the altitude where B29s were flying and destroy them before they could drop their bombs. Conventional Japanese fighters couldn't reach them. The J8M could inuka lit the engine, the rocket fired. The J8M leapt off the runway and climbed. Then the engine quit. The aircraft fell. Inazuka did not survive.

[00:19:57]Six more prototypes sat on the ground.

[00:20:00]None of them would ever fly. One month later, in early August 1945, one week before Japan surrendered, a different aircraft rolled onto a runway at Kisarazzu Airfield. The Nakajima Kika, Japan's first jet aircraft. It was inspired by Germany's MI262, the world's first operational jet fighter. But Kika was not a copy. The detailed technical documents from Germany had been loaded onto a submarine for transport to Japan, and that submarine was sunk by an American torpedo in the Atlantic. Japanese engineers received only a handful of photographs and basic specifications.

[00:20:44]They designed the rest themselves. Kika took off. It flew. Its engines were weaker than the Mi262s.

[00:20:53]Its range was shorter, but it flew. One week later, the war was over.

[00:21:01]If the Kika had been the only thing American teams found in Japan's aircraft factories, it would have been remarkable enough. But it wasn't.

[00:21:11]In storage depots and caves along Japan's coastline, they found something that had already seen combat. The Oka, a rocket powered piloted bomb carried beneath the belly of a twin engine Betty bomber to within 18 m of its target, then released. Three solid fuel rocket motors ignited, accelerating it past 600 mph, faster than any American fighter in service. The Americans called it Baka bomb. At Okinawa, 74 Oka were launched in combat. The results told the story of American air defense more than Japanese engineering. The Betty bombers carrying Oka were slow, heavy, and unmaneuverable.

[00:21:59]American combat air patrols intercepted them far from the fleet. Those that got through faced a wall of fire. 5-in guns.

[00:22:08]Bowars's 40mm cannons, URL 20mm batteries, layered defenses that turned the airspace around the fleet into a killing zone. Most Oka never reached their targets. The ones that did struck with devastating force, but the system that delivered them couldn't survive the gauntlet that American ships and pilots had built.

[00:22:33]When the war ended, thousands of Oka sat in storage along the Japanese coast, stockpiled for the defense against an American invasion that never came because America ended the war before it was necessary. But it was the factory floors that left the deepest impression on the American inspection teams. When engineers opened up the jet and rocket prototypes, they found two things side by side that didn't belong together.

[00:23:02]The aerodynamic designs were sophisticated. Swept wings, laminer flow calculations, intake geometries that rivaled anything coming out of American or German laboratories, and the materials holding them together were from another century. Wooden structural frames where aluminum should have been, civilian-grade electrical wiring, substitute alloys, improvised fasteners.

[00:23:29]The blueprints belonged to the 1950s.

[00:23:32]The materials belonged to the 1800s.

[00:23:35]American submarines had cut Japan's supply of raw materials to almost nothing. B-29s had burned the factories that processed what little remained. The naval blockade sealed the home islands.

[00:23:49]Japanese engineers kept building with whatever they could find. And the speed of American destruction outran the speed of Japanese invention. That is why none of these weapons changed the outcome.

[00:24:02]The weapons were one story. The men who captured, studied, and flew them were another. On a June morning in 1942, a Japanese pilot named Tatayoshi Koga launched from the aircraft carrier Ryujo as part of the strike force attacking Dutch Harbor, Alaska. He was flying an A6M0, the fighter that had owned the skies over the Pacific since the first day of the war. On his return flight, two bullets punctured his fuel line. Oil pressure dropped. Koga looked for a place to land and spotted a flat stretch of grass on a Coutan Island in the Alutians.

[00:24:45]He lowered his landing gear. That was his mistake. The grass covered a bog.

[00:24:51]The wheels dug in. The Zero flipped onto its back. Koga's neck broke on impact. 5 weeks later, a PBY Catalina on routine patrol spotted the overturned Zero in the marshland, nearly intact. It was pulled from the mud, shipped to San Diego, repaired, and made airworthy.

[00:25:15]And for the first time, an American pilot sat in the cockpit of the aircraft that had been killing his friends since Pearl Harbor. What the test flights revealed changed the air war. The Zero was extraordinarily maneuverable. It could outturn any American fighter at low and medium speeds. But its structure was fragile. It had no armor protecting the pilot, no self-sealing fuel tanks.

[00:25:42]its oil system was vulnerable to even minor damage. From these findings, American tacticians developed the doctrine that would govern every air engagement in the Pacific for the rest of the war. Never turn with a zero.

[00:25:57]Never engage in a slow speed dog fight.

[00:26:01]Dive from above. Fire in a single pass.

[00:26:05]Climb away using superior engine power.

[00:26:08]The pilots called it boom and zoom. That one wrecked airplane on a coutan island saved American lives for the next 3 years. The men who made this possible were the Technical Air Intelligence Unit, T A IU. From 1942 onward, small teams of engineers and mechanics operated near the front lines across the Pacific. They waited through jungle, crossed coral reefs, and searched crash sites in tropical swamps for salvageable Japanese aircraft. At Eagle Farm airfield in Brisbane, Australia, a TIU crew assembled a flyable Nakajima Key 43 Oscar from parts of five different wrecks. They flew it. They tested it against a Spitfire 5 in mock combat.

[00:26:59]Their conclusion, the Oscar outperformed the Spitfire below 20,000 ft. That information went straight to Allied fighter squadrons. Their biggest obstacle wasn't the Japanese. It was their own side. American troops stripped crashed enemy aircraft of anything portable. Compasses, instruments, control panels, swords, even personal items on captured submarines.

[00:27:26]The looting was worse. When American sailors boarded a 400 after her surrender, they took everything from officer swords to enlisted men's razors.

[00:27:36]Technical intelligence lost valuable data because every G I wanted to bring a souvenir home to his family. But the crown achievement of technical air intelligence came in October 1944 at the fighter conference held at Naval Air Station Puxent River, Maryland. A single captured zero TIC number five and A6M5 model recovered from Saipan in June 1944.

[00:28:07]Serial number 61-120 became the only Axis aircraft to participate. On September 6th, 1944, Navy test pilot Lieutenant Clyde Ceil Andrews made the first American flight of TIC5.

[00:28:24]Over the next weeks, 17 flights, 21 12 hours in the air. Then came the conference itself. T AIC5 flew against the F4U Corsair, the F6F Hellcat, the P38 Lightning, the P47 Thunderbolt, the P61 Black Widow, the Supermarine Seafire, and more. The test pilots who flew against that zero and some who flew it went on to build American aviation.

[00:28:57]Corki Meyer. He would rise to senior vice president at Grman Aerospace, the company that built the Hellcat, the fighter that broke the Zero's grip on the Pacific. Jack Woolams. He would become the first pilot to fly the Bell X1, the rocket plane that would break the sound barrier. Williams made the first glide flights. He was killed in a racing crash before the powered flights began. Chuck Joerger finished what he started. Woody Burke. He would fly the FH1 Phantom, McDonald's first jet fighter and the beginning of a dynasty of American naval jet aircraft. These men climbed into the cockpit of a Zero first. Then they went and built the jet age. When the war ended, General Hap Arnold ordered four of every type of Japanese aircraft preserved. One for the Army Air Forces, one for the Navy, one for the Royal Air Force, one for museums.

[00:29:59]115 Japanese aircraft were shipped back to the United States by the end of 1945.

[00:30:05]Almost nobody wanted them. America had already moved into the jet age.

[00:30:11]Propeller-driven Japanese fighters were yesterday's technology. Only six of the 115 were ever flight tested. 46 went to museums. The rest were crushed and melted down. The zero that had once terrorized every pilot in the Pacific became scrap metal in a warehouse in Ohio. But one survived. Tank 5, after 190 hours of flight testing after the fighter conference after being rung out by some of the best pilots in the country, was declared surplus by the Navy and put up for sale.

[00:30:49]A young man named Edward Maloney bought it. Maloney wanted to build an aviation museum, the first west of the Mississippi. He bought the Zero at scrap prices. He didn't care about its combat record or its intelligence value. He cared that it was real and that it might disappear if no one saved it. Today, TIC5 sits at the Plains of Fame Air Museum in Chino, California. It is the last flyable zero in the world. Once a year, its Nakajima Sakai engine turns over and the sound it makes is the last echo of the air war over the Pacific. In a few short months after the war, American teams opened every door in defeated Japan. They found a submarine that could launch bombers against New York and disappear without a trace.

[00:31:43]Torpedoes that had been sinking American warships for 3 years with technology the Navy refused to believe existed. Paper balloons that crossed the Pacific on a wind current that Japanese scientists had mapped 20 years before anyone else.

[00:31:59]Jet aircraft and rocket interceptors assembled in bombedout factories from scraps of wood and civilian wire. and the Zero, the fighter that ruled the Pacific sky, sitting by the thousands on airfields with no fuel, no pilots, and no war left to fight. The enemy had poured everything it had, its engineering, its resources, its people into these final weapons. None of it was enough because across the Pacific, American shipyards were building warships faster than Japan could sink them. American factories were producing aircraft faster than Japanese pilots could shoot them down. And the men who fought that war, the sailors, the pilots, the marines, the engineers defeated everything the enemy put in front of them. Those weapons are quiet now. The wreck of I400 lies in 2300 ft of water off Hawaii. Longlands torpedoes rest behind glass in museums. Fragments of fugo balloons sit in federal archives. Oka rockets stand on pedestals at the Smithsonian.

[00:33:13]And take five, the last zero, still flies once a year in Chino, California.

[00:33:20]The sound of its engine is the last living sound from that war. A lot of you watching this had fathers or grandfathers who came home from the Pacific. Some of them may have seen a long lance tear through a ship at night and never knew what hit them. Some may have watched a zero come out of the sun.

[00:33:37]Some may have found strange wreckage in a field and never learned what it was.

[00:33:42]They came home and told those stories at dinner tables across America, stories no history book will ever record.

[00:33:50]Every year there are fewer people who can tell them. If you have one, write it down. Put it in the comments. Don't let it disappear.