At 3:30 in the morning on December 7, 1941, five Japanese midget submarines slipped away from their mother ships and began the slow, careful approach to the mouth of Pearl Harbor. Each boat carried two men. Each man understood, though no one said the word aloud, that the mission was not expected to end in return. One of those men was Kazuo Sakamaki, twenty-three years old, a junior officer who had already written his death poem and clipped a lock of his hair for his family to bury.

In the final hours before launch, his crew discovered that the gyrocompass on his midget submarine was broken. There was no time to repair it and no spare part. Sakamaki was told he could still refuse. He went anyway.

The attack on Pearl Harbor was already four hours old when the submarine H-19 ran aground for the third time that night, scraping against the coral reef off Bellows Field. The USS Arizona was burning in Battleship Row behind him, nearly a thousand of her crew dead. His batteries were nearly exhausted, his gyrocompass had failed hours earlier, and he and his crewmate, Kiyoshi Inagaki, had been sealed inside the steel hull for almost twenty hours. Inagaki drowned in the surf.

Sakamaki reached the beach, tried to set the scuttling charges on his stranded submarine, and failed. He collapsed on the sand. When the sun rose on the morning of December 8, he became the first Japanese prisoner of war of the Pacific conflict. He had intended to die.

He had been trained to die. Even suicide had failed him. None of this was supposed to happen. The Imperial Japanese Navy went to war with what should have been one of the finest submarine fleets in the world.

Its boats were larger than Germany’s, its torpedoes more advanced than America’s, its crews among the most disciplined anywhere. Over the next six months, that fleet failed so completely and so systematically that historians would argue about why for a century. The roots of that failure lay in a room in Tokyo in the 1920s, where a man named Nobumasa Suetsugu shaped the submarine doctrine that would doom thousands of sailors he never met. Suetsugu was an artillery officer.

He never commanded a submarine, not once, not for a single day. He learned about submarines by observing them from the decks of other nations’ warships. Yet he rose to become the most powerful voice shaping undersea warfare in the Imperial Navy, and he ended the careers of any officer who disagreed with him. His vision was simple and fatal.

The submarine was not a hunter of merchant ships, hunting that was beneath its dignity. The submarine was a weapon for the decisive battle, the Kanto Kessen. It would locate the American fleet, shadow it, ambush it, and sink enough American battleships before the main battlefleets met to even the odds. Japanese submarines would attack only battleships.

Destroyers and cruisers were not worth the risk of being detected. By the 1930s, the submarine service had become an echo chamber. Everyone agreed. Everyone had to agree.

The instruments were extraordinary. The Type A, B, and C submarines could exceed twenty-three knots on the surface and cross the Pacific without refueling. The Type 95 torpedo ran on pure oxygen and kerosene, leaving almost no wake, carrying a nearly four-hundred-kilogram warhead at up to eighty knots over almost eleven kilometers. The American Mark 14 of the same era was so unreliable that captains watched it bounce off enemy hulls.

Japan’s torpedo was a generation ahead of anything its enemies possessed. But it was aimed according to a doctrine that was already wrong. In 1938, the Navy held its first serious submarine fleet maneuvers. They failed.

Submarines could not communicate with the fleet, could not keep pace with it, could not coordinate attacks. The reconnaissance seaplanes, essential to the doctrine, proved nearly impossible to organize in practice. A rational navy might have paused. The Imperial Navy doubled down, tightening orders and restricting targets even further.

In late 1940, the Navy ran a final exercise, a simulation of commerce warfare against Japanese merchant ships using a shore-based command system copied from the Germans. Within days, submarines scored more than a hundred simulated victories. It was proof, right before their eyes, that the doctrine on which the entire submarine fleet had been built was wrong. The Navy drew the opposite conclusion.

The lesson, they decided, was not that they should hunt merchant ships. The lesson was that their own merchant marine was dangerously vulnerable to submarines that communicated constantly by radio. They correctly identified a problem and prescribed the wrong cure. The last chance to change course slipped past unnoticed.

Thirty submarines were sent to Hawaii for the Pearl Harbor operation, more than the entire American Pacific Fleet then in service. They were divided into four groups: two far to the east watching the sea lanes, a patrol line around Oahu to destroy the American fleet as it fled, escorts for the carrier striking force, and the special group of five midget submarines. The midget submarine attack achieved nothing. Four of the ten men died.

One was captured. On the morning of December 10, the submarine I-70 was cruising on the surface northeast of Oahu, hunting American warships. Her captain believed, as most Japanese captains still believed, that the American carriers were fleeing for California. They were not fleeing.

The USS Enterprise was hunting. A Dauntless dive bomber flown by Lieutenant Clarence Dickinson spotted the submarine and dropped a bomb that missed close enough to damage her. A second bomber returned that afternoon and did not miss. The I-70 capsized and sank with her entire crew, the first Japanese warship lost in the Pacific War.

The weapon built to sink American carriers was destroyed by an aircraft launched from one. The Japanese did not understand what this meant, because their doctrine did not permit them to imagine it. On December 9, a Japanese submarine sighted an American carrier east of Hawaii and radioed her position. Tokyo interpreted the report as proof that the carrier was fleeing toward California.

A half-dozen submarines were ordered east in pursuit, thinning the patrol line around Oahu. The carrier was not fleeing. She was returning to Pearl Harbor to rearm. Behind her came the Lexington, the Saratoga, the Yorktown, and the damaged survivors of December 7 limping back for repairs.

Had the Japanese submarines held their iron ring around Oahu, American ships would have passed almost directly over their periscopes, nearly the entire surviving Pacific Fleet passing one by one within torpedo range. The trap was already broken. Japanese submarine commanders operated under rigid rules about how many torpedoes could be fired at a target. If the first salvo missed and the commander could not close for a perfect second shot, he was expected to break off.

Surfacing and pursuing with the deck gun was considered vulgar. Attacking smaller ships was considered wasteful. A captain who had expended his torpedoes on an escaped battleship sometimes let an American cruiser pass unharmed. It was not cowardice.

It was training. Certain kinds of victory were beneath their dignity, and certain kinds of enemies were beneath their dignity. This training proved stronger than any evidence placed before their eyes. On January 11, 1942, the submarine I-6 sighted the carrier USS Saratoga.

Commander Minobu Inaba fired three torpedoes. One struck, tearing open the hull below the waterline. Six sailors died. The great ship listed, stabilized, and limped away to Bremerton for repairs.

She would not fight again for six months. Inaba reported her sunk. Tokyo celebrated. But the truth was stranger than the lie.

The Saratoga was not present at the Battle of the Coral Sea. She was not at Midway. Her absence made possible events no one could yet foresee. The only real triumph of the Japanese submarine fleet would eventually haunt it.

On January 24, off the west point of Java, the I-60 met the British destroyer HMS Jupiter. The Japanese submarine, already damaged from a depth-charge attack, surfaced in the darkness to charge her batteries. The two ships came so close that the Jupiter’s forward guns could not depress enough to fire. Steel scraped against steel in the black water.

The Japanese captain ordered his deck gun manned. The submarine’s 4. 7-inch gun scored a direct hit on the destroyer’s gun mount, but the Jupiter’s 20mm guns cut down every gun crew the submarine sent up. The I-60 could not dive.

She could not run. Sailors kept coming up the hatch until there were no more to send. Of her crew of ninety, three returned home. Three days later, off Darwin, Australia, the minelayer submarine I-124 was the target of a different kind of killing.

Her torpedo attack on the tanker Trinity failed, the trail of her older torpedo was spotted, and three Australian corvettes and two American destroyers converged. What followed was not a fight. It was a slow, methodical, exhausting execution. Depth charges were dropped all morning, all afternoon.

The corvettes returned to Darwin to rearm, came back, and dropped more. The attacks continued nearly twenty-four hours. When divers finally reached the wreck years later, they found something astonishing: the hull was largely intact, battered and cracked but still recognizable. She had not died from one fatal blow but from the accumulation of many small ones.

Eighty men were sealed inside her. They are still there. On January 27, the American submarine USS Gudgeon received a coded message from Pearl Harbor listing three Japanese submarines and their expected course and speed on the return from Hawaii. Captain Elton W.

Grenfell accepted the message without asking how Pearl Harbor knew. The answer, not revealed for decades, was that American codebreakers had already broken the Japanese naval code. Every signal, every course, every position report the Japanese submarine fleet sent home was being decrypted within hours. The Japanese did not know.

They would not know. They would keep transmitting in the same broken code for the rest of the war. The Gudgeon did not find the submarines named in the message. She found another, the I-73, running on the surface.

Three torpedoes left her tubes. Two exploded. The I-73 became the first enemy warship ever sunk by an American submarine. The war reached the American mainland on the night of February 23, 1942, when the submarine I-17 surfaced off Santa Barbara, California.

Her captain, Lieutenant Commander Kozo Nishino, opened fire on an oil field near the beach with his deck gun. The damage was minimal: a pier, a pump house, a walkway. No one was killed. But it was the first attack on the American mainland by a foreign power since the War of 1812.

Two nights later, the anti-aircraft batteries of Los Angeles fired more than fourteen hundred shells into an empty sky. Five civilians died from falling shrapnel and heart attacks during the panic. There were no Japanese aircraft over California. There never had been.

Four days before the Santa Barbara attack, President Roosevelt had signed Executive Order 9066. In the aftermath of the shelling and the panic, the government began removing more than 120,000 Japanese-American civilians from their homes. Communities were uprooted and sent behind barbed wire for the duration of the war. Nishino had not won a military victory.

He had changed the lives of more than a hundred thousand people who had done nothing to him. In early March 1942, the Imperial Navy tried to attack Pearl Harbor again, not with submarines but with long-range flying boats. Two four-engine H8K aircraft would take off from the Marshall Islands, refuel at sea from Japanese submarines waiting at a remote atoll called French Frigate Shoals, and bomb the drydocks and repair facilities at Pearl Harbor. The mission was called Operation K.

Seven submarines were stripped from their patrol posts to sit motionless at the coral atoll and pump fuel into the aircraft. The flying boats took off on March 4, refueled, and flew toward Hawaii. In the darkness, they could not see Pearl Harbor. They dropped their bombs on the slopes of Mount Tantalus, a few kilometers inland.

They destroyed an empty forest. The great second attack on Pearl Harbor had achieved nothing. A month later, six of the older submarines were sent into the Indian Ocean to support an air raid on Ceylon. They sank seven merchant ships.

Nagumo’s aircraft sank the carrier HMS Hermes, two heavy cruisers, and more than a hundred thousand tons of shipping in the same operation. The submarines remained invisible in the official accounts. The true test came in early May 1942. Six Japanese submarines were deployed to support the invasion of Port Moresby.

On the evening of May 4, the I-21 under a cautious captain named Matsumura was cruising south of the New Hebrides when he raised his periscope and saw something: American warships, destroyers in a loose formation heading southeast. He observed them for a long time, counted them, noted their course and speed. He knew that where escorts were, larger ships were almost certainly not far behind. He lowered his periscope and decided not to launch his reconnaissance seaplane.

The reasons were sound. Launching the seaplane meant nearly an hour of running on the surface in daylight, dangerously close to American escorts. If anything went wrong, if the aircraft was spotted and shot down, if recovery took too long, the mother submarine would be alone in waters where American destroyers were already moving. Matsumura chose caution.

By any reasonable standard, no one could blame him. But fifty kilometers behind that outer screen, hidden by distance and haze in the curve of the sea, sailed the USS Lexington and the USS Yorktown together, nearly 150 aircraft aboard, more than five thousand men, exactly the target for which the entire Japanese submarine fleet had been built. They were within range. Had Matsumura launched his seaplane for even one hour, the pilot would have seen them and radioed their position.

Six submarines could have closed in the darkness. The Battle of the Coral Sea began forty-eight hours later. During the entire battle, the first carrier battle in history, the first time two fleets fought without ever seeing each other, no American ship was sunk by a Japanese submarine. Six of the best submarines of the Imperial Navy lay at their posts.

Six periscopes searched. Nothing happened. The Saratoga was still in repair at Bremerton when the Coral Sea was fought. Had she been present, three American carriers against two Japanese might have been the crushing American victory the Imperial Navy had feared for twenty years.

Instead it was two against two, a draw that was an American strategic victory only because the Japanese called off the invasion of Port Moresby. The Yorktown was damaged but not destroyed and was repaired in a frantic seventy-two-hour race so she could fight at Midway. The greatest achievement of the Japanese Imperial Navy’s submarines in six months of war was making it easier for the Americans at Coral Sea and guaranteeing that the Yorktown would still be able to sail and fight at Midway, the battle that would break the backbone of the Japanese carrier fleet. The balance sheet from December 7, 1941, to May 8, 1942: the I-70 destroyed by an American dive bomber, the five midget submarines lost at Pearl Harbor, nine men dead and Sakamaki captured, the I-60 destroyed by HMS Jupiter with eighty-seven dead, the I-124 destroyed off Darwin with eighty men still aboard, the I-73 destroyed north of Midway, the first Japanese warship sunk by an American submarine.

In exchange, the entire submarine fleet had sunk about forty-two Allied merchant ships, mostly small, most as by-products of other missions. They had sunk three military ships of any significance. They had put one carrier out of action for six months. They had sunk no battleships.

They had sunk no fleet carriers. They had sunk no Pacific Fleet cruisers. In Berlin, Admiral Karl Dönitz’s U-boats were sinking half a million tons of Allied shipping every thirty days. The arithmetic was final.

The doctrine had failed. On June 4, 1942, four Japanese carriers sank in a single afternoon at Midway. The largest naval disaster in Japanese history. Two days later, the submarine I-168 under Lieutenant Commander Yahachi Tanabe crept silently toward a damaged American carrier lying dead in the water.

It was the USS Yorktown. Tanabe was thirty-six years old, steady, patient. He had been given the mission for which the entire doctrine of Kantai Kessen had been designed. He worked his way through the screen line and fired four torpedoes at short range on the afternoon of June 6.

Two struck the Yorktown, finishing the work Japanese aircraft had begun three days earlier. One torpedo struck the destroyer USS Hammann alongside, which sank in less than four minutes. Almost two hundred American sailors died. It was the greatest success a Japanese submarine achieved in the entire war.

And it came too late. The four carriers were already lost. Midway was already decided. The war in the Pacific was strategically over, though fighting would continue for three more terrible years.

Tanabe brought the I-168 home. He was celebrated. He survived the war. But behind him, the last spark of Suetsugu’s doctrine was already extinguished.

The submarines would still fight. They would still sink ships. But over the next three years, they would slowly be converted into freighters, carrying rice to Guadalcanal, ammunition to Kolombangara, medical supplies to starving garrisons at Rabaul. The finest long-range submarines in the world, built to hunt battleships across sixteen thousand kilometers of ocean, were reduced to carrying drums of gasoline in the dark to islands their army could not hold.

Many never returned. Kazuo Sakamaki was first held on Sand Island in Hawaii, then shipped east to a prisoner-of-war camp in Wisconsin called Camp McCoy, far from the sea. He was for a long time the only Japanese prisoner held by the Americans, designated POW Number One. When other Japanese prisoners finally arrived, they were told not to look at him.

He was an object of shame, a man who had failed to die and was living on borrowed, dishonorable time. Sakamaki asked permission to commit suicide. His request was denied. He asked for pen and paper instead and wrote a book published in Japan after the war, titled I Attacked Pearl Harbor.

It was honest and restrained. He wrote about the broken compass. He wrote about Inagaki drowning in the surf. He wrote about waking up on the beach and realizing that even suicide had been denied him.

After the war, Sakamaki returned to Japan and found work at Toyota. He rose steadily within the company, and in the 1980s he ended his career as president of Toyota do Brasil. He married, had children, grew old, and lived to eighty-one, dying in 1999, fifty-eight years after the night he tried to die at Pearl Harbor. For fifty-eight years he watched the empire he served collapse and be reborn as something entirely different.

He watched the Imperial Navy dissolve. He watched his own midget submarine, the HA-19, displayed as a war trophy as it toured the United States selling war bonds. He was the last surviving witness to a plan that had cost the lives of nearly everyone involved. Nobumasa Suetsugu, the artillery officer who built the doctrine, died in 1944.

He did not live long enough to see the end. He did not live to see his submarines sink while carrying sacks of rice to starving soldiers on jungle islands. Sakamaki saw it all. Somewhere in the North Pacific, in waters more than a mile and a half deep, the wreck of the I-70 still lies where she sank on December 10, 1941, the first Japanese warship lost in a war that would cost more than two million of her countrymen their lives.

She was a submarine. She was brought down by an aircraft. Everything you need to know about the Japanese submarine campaign of World War II is contained in that single fact. The hunter had become the prey.

The weapon had become the target. And the men who served aboard her and aboard the boats that followed went down believing in a doctrine that was already broken before they ever put to sea.