When a “Broken” American Submarine Accidentally Discovered a Hidden Japanese Base

In the vast and unpredictable waters of the Pacific, the USS Harter was a submarine facing impossible odds. Its mission, on June 6th, 1944, seemed straightforward enough: patrol the waters off Tawi Tawi in the southern Philippines, report on Japanese naval movements, and avoid engagement. But for Lieutenant Commander Samuel “Sam” De, the routine assignment would become one of the most extraordinary moments in submarine warfare—a gamble that would alter the course of the Pacific War and leave a legacy of innovation and courage that would echo through naval history.

Sam De wasn’t a man who followed doctrine. In a world where conservative tactics and caution ruled the seas, De’s unorthodox approach was a breath of fresh air for a fleet suffocated by failure and losses. For the crew of the USS Harter, June 6th would mark the day that De defied everything they were taught at naval school and executed a mission that would make history—by charging straight into the jaws of death.

The events unfolded under the quiet shroud of dawn. As the Harter surfaced just long enough to take a quick look through the periscope, De’s sharp eyes locked onto an enemy convoy: three Japanese destroyers were bearing down on them at full speed. They were closing in fast—1,200 yards and shrinking.

The standard response for any submarine in such a situation would be to dive deep, go silent, and pray the destroyers passed over without detecting the submarine. This was the textbook strategy. It was a tactic that had kept submarines alive for years, allowing them to survive despite the overwhelming odds stacked against them.

But Lieutenant Commander De wasn’t interested in the textbook. His mind raced as he processed the situation in a way most would have called reckless. He ordered the Harter to aim directly at the lead destroyer, with torpedoes primed for a head-on assault. He wasn’t going to flee. He was going to fight.

“Captain, they’re right on top of us,” said Frank Lynch, the Harter’s executive officer, his voice cracking with panic as the destroyers charged at full speed.

The situation was indeed dire. The Harter, at full speed, could only manage a maximum submerged speed of nine knots. Meanwhile, the Japanese destroyers were steaming at 35 knots, their sonar-equipped systems already locking onto their target. The standard protocol would be to dive deep and avoid confrontation—but De knew something the others didn’t: sitting back and waiting would guarantee their destruction.

Instead, he ordered, “Battle stations, fire tubes one, two, and three,” without hesitation. The destroyers were closing in fast, their heavy wake creating turbulence as they sped toward the Harter. It was a decision that no textbook would ever recommend. To fire torpedoes at point-blank range—against a destroyer, the fastest and most dangerous predator in the ocean—was considered suicide.

But Sam De had no intention of dying like the others. With his mind calculating the angles, his hands steady on the periscope, and his crew braced for impact, De’s gamble became a singular moment of tactical genius. At 900 yards, the Harter fired three torpedoes.

The explosion was immediate. Two of the torpedoes hit the Japanese destroyer Minatsuki, tearing its hull in half. The explosion was so violent that the ship’s bow rose from the water before sinking into the abyss. The Japanese destroyer sank in just 90 seconds. The crew of the Harter cheered as they braced for what was about to come next.

But the victory was far from secured. Within moments, the remaining five destroyers in the convoy had turned on the Harter, knowing exactly where she was and preparing to unleash a barrage of depth charges. With every passing second, the Harter was closing in on the inevitable. Seven destroyers were now on the hunt, and De’s crew had no choice but to endure the 149 depth charges that followed.

Inside the submarine, the crew was shaken by the intensity of the explosions. Cork insulation rained down from the ceiling as the hull groaned under the pressure of the blast. The lights flickered, and the crew braced themselves for the worst. Oxygen levels plummeted. Yet, despite the chaos, De stayed calm. He was unflinching, calculating, and making decisions that defied the odds. Every minute felt like an eternity.

Despite all odds, the Harter survived the barrage, plunging deeper into the abyss, slipping away from the angry destroyers that had relentlessly pursued her. For 40 minutes, the submarine sat motionless, waiting, listening for the slightest sound that could give away their position. The Japanese destroyers had assumed they had succeeded in sinking the American submarine, and they began to break off.

De’s gamble had paid off—at least, for the moment.

The following morning, after hours of hiding and surviving, De surfaced the Harter once more. His crew was exhausted, but they were alive. What they didn’t know at the time was that their survival would change the entire course of the war. De had discovered something invaluable—something so dangerous to the Japanese that they would abandon their own strategic base because of it.

Over the next 48 hours, De meticulously followed the convoy. He tracked their every movement, knowing that his crew had discovered the most important intelligence of the war— the location of Japan’s entire mobile fleet, hidden in the waters of Tawi Tawi. This fleet, which included the battleships Yamato and Musashi, was the largest concentration of Japanese naval power since the Battle of Midway. Yet it was all now exposed to American intelligence thanks to one commander’s bold decision.

De’s crew sent the urgent message to Pearl Harbor, alerting them of the discovery. The Japanese, unaware that their fleet had been uncovered, had no idea that the American Navy now knew exactly where they were. The threat they posed to the Allied forces had been neutralized, not by a massive naval assault, but by one lone submarine commander who was willing to take a risk no one else dared to take.

The fallout from De’s actions was immediate. Japanese high command, upon learning that their fleet had been discovered, ordered their ships to withdraw from Tawi Tawi and change their entire strategy. Meanwhile, the American fleet, armed with the knowledge of the Japanese fleet’s movements, could now take the upper hand in the Battle of the Philippine Sea, which would go on to become one of the most decisive naval victories of the Pacific War.

De’s tactics were groundbreaking. While the Navy had long adhered to the doctrine of avoiding destroyers at all costs, De’s actions proved that aggressive tactics, when executed with precision, could be the key to victory. By the end of the war, his “down the throat” strategy—attacking destroyers head-on—would become standard training for every submarine commander in the Pacific.

But De’s success didn’t come without consequences. His unorthodox methods earned him both praise and criticism within the Navy. Some considered his tactics reckless, while others saw them as a necessary evolution in submarine warfare. De, however, remained focused on one thing: results. In four days, his crew had sunk three destroyers and disrupted the Japanese Navy’s entire battle plan. The Harter had changed the game, and De had proven that sometimes, the impossible tactic becomes the winning tactic if someone has the courage to try it.

In the following months, De would continue to test his theories, sinking more Japanese ships and gathering invaluable intelligence. But it was his actions during that 80-hour pursuit of the Japanese fleet—when he risked everything to attack, to charge into the jaws of death—that solidified his place in history.

On June 9th, 1944, De would face another challenge when his Harter engaged yet another Japanese destroyer. This time, the attack was even more successful. The Harter sank the Japanese destroyer Tanakazi in 90 seconds. Four destroyers in just four days. The Japanese Navy, once confident in their ability to protect their fleet, was now reeling from the damage.

The war in the Pacific was shifting, and Sam De’s audacity had played a critical role in turning the tide. His boldness forced a reevaluation of submarine tactics, allowing for a more aggressive, more successful approach to warfare.

When the war ended, Sam De had earned four Navy Crosses and the admiration of his peers. His actions aboard the USS Harter had changed the course of the Pacific War and set the stage for future submarine operations. Yet, despite his success, De remained humble. He didn’t seek fame or recognition. Instead, he focused on his crew, ensuring that they understood the power of taking calculated risks and thinking outside the box.

Slade De’s story is one of courage, intelligence, and relentless pursuit. It’s a reminder that sometimes, the greatest victories don’t come from waiting for the perfect opportunity—they come from creating one, no matter how dangerous it may seem. Sam De didn’t just fight a war—he changed the way submarines would fight forever.