76 Years After This U.S. Navy Submarine Was Lost, Divers Unraveled Its Terrible Fate

Some 15 months after the U.S. officially became involved in World War II, the USS Grenadier set off on its final mission. And in the Strait of Malacca, between Sumatra and the Malay Peninsula, it met its unfortunate end. But what happened to the stricken submarine after the bombs fell? For years, it seemed like the mystery would lie dormant beneath the waves... until 2019.

Did the Grenadier’s 76-man crew sink with the vessel towards a watery grave? Or perhaps they escaped, only to endure further horrors in one of the conflict’s most violent theaters? After they were attacked, the crew scrambled to fix the damage, but they knew their time on the submarine was numbered. The men found themselves facing an uncertain – and terrifying – fate.

For years, nobody knew the full story of what happened to the Grenadier. Like so many other missions during the war, it seemed to simply vanish out of history. Then, trawler crews in the Strait of Malacca began to report something catching their nets beneath the surface. Diving down hundreds of feet, researchers uncovered a forgotten secret – allowing the tale of the long-lost submarine to finally be told.

The Grenadier first set sail from Maine in November 1940. It took its moniker from the fish of the same name, a creature that, ironically, thrives in the ocean’s depths. Weighing in at close to 1,500 tons, the vessel was more than 300 feet in length and capable of reaching more than 20 knots on the surface. The Grenadier was a beast — which is exactly why it was sent on some of the most dangerous naval missions.

Five months after its launch, the Grenadier was commissioned by the U.S. Navy, meaning it was destined to play a role in the conflict to come. By that time, World War II was already raging across much of the world, and before long the United States would be drawn into the fray. Following a trial run amid the Caribbean, the submarine arrived back in Maine – just a month before the raid on Pearl Harbor.

On December 7, 1941, Japanese forces launched an unexpected assault on the Hawaiian port, which officially brought the U.S. into World War II. The Grenadier was soon shipped out to the Pacific, initially docking at Pearl Harbor before setting sail for Japan. But even though its crew spotted enemy vessels several times, they didn’t succeed in sinking any of them.

All that, though, would change during the Grenadier’s second mission, which took the submarine to the shipping lanes off Japan and Taiwan. Early in May 1942, the vessel sank its first target: the Japanese transporter Taiyō Maru. At the time, the ship was carrying several important scientists, and it’s believed that the incident played a part in turning the tide of the conflict.

The sub's missions only got more dangerous as her crew refined their skills. Next, the Grenadier was moved to Midway, an island in the Pacific Ocean approximately halfway between Asia and North America. With the Imperial Japanese Navy closing in on the American territory, U.S. Navy commanders had begun gathering their forces for a brutal counter-offensive. And ultimately, it paid off.

With the help of submarines such as the Grenadier, the U.S. Navy fought off the enemy, decimating the Japanese fleet in the process. Today, the Battle of Midway is considered one of the most significant naval conflicts of all time and a turning point in the Pacific War. But WWII would still continue for another three years, and the submarine was soon assigned a new mission.

Fresh from their success at Midway, the crew of the Grenadier began their next mission: searching the waters near the island of Truk in the central Pacific. Throughout the war, the region served as a Japanese station, and the waters were thick with enemy vessels. But Axis planes overhead prevented the submarine from sinking any of the targets, and the crew sailed for Fremantle in Australia instead.

From there, the Grenadier set off on its fourth mission. With the failure of their previous mission looming overhead, the crew knew they needed a victory. Sure enough, over the course of two months, the crew managed another sinking, this time the Japanese tug Hokkai Maru. Then, on New Year’s Day 1943, the submarine embarked on its fifth wartime outing.

This time, the Grenadier was more successful. Over just seven weeks, the crew managed to sink three Japanese vessels and cause extensive damage to a couple more. These were the victories that the crew had so desperately needed, and with their hopes renewed, the submarine eventually returned to its base in Fremantle. There, preparations began for the Grenadier's next mission. No one could've known that it would also be the sub's final mission.

In mid-March 1943 the Grenadier left its base en route to the Strait of Malacca, a 600-mile body of water that connects the Pacific and Indian oceans. By that time, the Japanese had established a strong foothold in Southeast Asia, and Allied units were gathering in the hopes of fighting them off. It was up to the Grenadier to slow the spread of Japanese influence in the area.

It wasn't long before they encountered their target. On April 6th, the crew of the Grenadier spotted and sank a Japanese freighter near the coast of Phuket, Thailand. But, as it turned out, that success would be their last. Fourteen days later, a couple of Japanese vessels came within sight of the submarine, setting it on its fateful course.

Thanks to a report written by Lieutenant Commander John A. Fitzgerald, the man in charge of the Grenadier, we know what happened next. After spotting the enemy vessels, the crew of the submarine prepared to launch an attack. And to increase speed, they decided to surface — an incredibly risky move, but one that would pay off in spades if they could outrun the enemy.

But before the Grenadier could close in on the two ships, Fitzgerald wrote, an aircraft was spotted overhead. Hoping to avoid enemy fire, the crew navigated the submarine swiftly beneath the waves. But by that point, the Grenadier had already been spotted by the enemy aircraft. The bomber then dropped its load, hoping to destroy the American vessel below.

As the Grenadier plunged to a depth of more than 100 feet, Fitzgerald believed they’d made good their escape — but not for long. A series of blasts tore through the submerged vessel. Even deep underwater, the Japanese bombs had hit their target. And so the submarine dropped even further beneath the surface. The deeper they sank, the more dire the crew's situation became.

Eventually, the Grenadier settled on the seabed some 250 or so feet down. By that point, things were looking bleak. The submarine had sustained extensive damage, and all power had been lost – leaving the crew to stumble around in the dark. To make matters worse, a blaze was threatening to tear through the entire craft. Disaster followed the crew at every turn.

For the next 13 hours, those aboard the Grenadier struggled to fix the damaged vessel. And miraculously, after night had fallen, they made it back up to the surface. By that point, though, it’d become clear that the craft could go no further under its own steam. Now drifting in the Strait of Malacca, the men were swiftly running out of options.

Aiming to move the Grenadier nearer to land, Fitzgerald instructed the crew to fashion a makeshift sail. It was a last-ditch effort at escape, one that Fitzgerald and the crew knew was a long shot. Sure enough, as the sun rose the next morning, it quickly became apparent that their efforts had been in vain. There on the horizon were a pair of Japanese vessels, heading straight for the submarine’s location.

Unable to perform another dive, the crew was forced to accept the inevitable: they’d soon be captured by their enemy. But they weren’t going down without a fight. As the men set about destroying any classified files on board, an enemy aircraft approached – only to be fought off by the Grenadier’s guns. Of course, they were ultimately outgunned and outmanned.

Eventually, the crew had little choice but to scuttle the doomed submarine to prevent it from ending up in enemy hands. They abandoned the vessel and watched as it disappeared beneath the waves. Stranded in the ocean, the men could only wait helplessly to be picked up by Japanese ships. And sadly, the sinking of the Grenadier would only be the beginning of their ordeals.

Before long, Japanese ships had plucked all 76 of the Grenadier’s crewmembers out of the water and taken them to the Malaysian town of Penang. There, they were housed in a repurposed school and subjected to intense interrogations by the Japanese. According to Fitzgerald, the men’s captors used torture to try to coerce them into revealing classified information.

Months later, the men from the Grenadier found themselves in Japanese prison complexes. But despite the change in location, conditions didn’t improve. Instead, according to reports, they were so badly treated that several died while in captivity. It was months — perhaps years — of torture, and those who survived undoubtedly wondered if the war would ever end.

The war eventually ended, and the surviving men from the Grenadier were able to return home. But what of the vessel that had carried them to the Strait of Malacca? By the time that hostilities were over, the war had claimed more than 50 American submarines. And many of them, such as the Grenadier, were gone without a trace.

For decades, the final resting place of Fitzgerald’s ill-fated vessel remained unknown. And as time passed, the men who had served on her raised families, grew old, and died. Then, in 2019 the sole surviving crew member passed away – the same year that a startling new chapter in the submarine’s story was revealed.

That October, a team of divers succeeded in locating what they believed to be the wreck of the Grenadier. So how did they manage to track it down after all these years? The trail began with a Belgian named Ben Reymenants, a Phuket-based diver who’s no stranger to making headlines.

When a young soccer team went missing in a cave in Northern Thailand back in 2018, Reymenants was one of the divers who volunteered to locate them. Eventually, the boys were saved thanks to the efforts of these rescue teams. And in September of that year, the Belgian was presented with an award by the Thai king in recognition of his efforts.

According to the Associated Press, Reymenants isn’t just a hero – he also hunts for lost wrecks in his spare time. In fact, Reymenants claims that he’s spent several years researching the potential locations of sunken vessels. And by picking the brains of Phuket fishermen, he’s identified a number of leads.

By asking the locals if there are any areas of the ocean in which their nets became snagged, Reymenants was able to pinpoint the locations of possible anomalies. He then used sonar technology to take a closer look at the objects. But he wasn’t working alone. Alongside him were Jean Luc Rivoire from Singapore, Lance Horowitz from Australia, and Benoit Laborie from France.

On Laborie’s boat, the four men patrolled the oceans off Phuket in search of lost wrecks. And in October 2019 they struck gold. According to the sonar, there was a large object at the bottom of the Strait of Malacca, some 250 feet or so beneath the surface. Reaching it, though, would not be straightforward. Accessing shipwrecks usually isn't as simple as it looks.

According to the Professional Association of Diving Instructors, scuba divers are typically limited to depths of up to 130 feet. To reach this object, then, Reymenants and his team would need to use specialist equipment. Equipped with a custom blend of gases including helium and nitrogen, they were able to descend to 280 feet, though could only remain there for fewer than ten minutes.

“We didn’t really have too much time,” Horowitz explained in a September 2020 interview with Live Science — a massive understatement, clearly! But despite the limits of the dive, they saw enough to confirm that they’d found what they were looking for. It was a submarine wreck, that much was certain – but one much larger than any of them had foreseen.

“We weren’t able to swim around the whole wreck… it kind of disappears off in either direction,” Horowitz continued. Plus, the wreck was undoubtedly rusted with age, completely waterlogged, and riddled with barnacles. Back on the surface, the team turned to local records in the hopes of identifying the mystery vessel. But ultimately, they had to return to the submerged site in search of answers.

“And so we went back looking for clues, nameplate, but we couldn’t find any of those,” Horowitz told the Associated Press in September 2020. “And in the end, we took very precise measurements of the submarine and compared those with the naval records.” Through this process, the team became convinced that they’d located the wreck of the Grenadier.

According to Horowitz, the measurements of the wreck perfectly matched up with those on record for Fitzgerald’s lost submarine. He said, “They’re exactly, as per the drawings, the exact same size. So we’re pretty confident that it is the USS Grenadier.” But it wasn’t just themselves who they needed to convince. You see, the research team couldn't just claim the wreck to be the Grenadier.

Over the course of five months and half a dozen dives, the team assembled a portfolio of documents to support their claim that the wreck is that of the Grenadier. And finally, in September 2020 they announced their find. Currently, the U.S. Naval History & Heritage Command is in the process of verifying the historic discovery.

According to the Associated Press, it isn’t uncommon for wreck-hunters to reach out to the Navy to confirm discoveries. Dr. Robert Neyland, head of the Underwater Archaeology Branch, explained, “A complete review, analysis, and documentation may take two months to a year to complete.” For some, this final chapter in the story of the Grenadier has been a long time coming. “This was an important ship during the war and it was very important to all the crew that served on her,” Horowitz said.

“When you read the book of the survivors, that was, you know, quite an ordeal they went through. And to know where she finally lies and rests, I’m sure it’s very satisfying for them and their families to be able to have some closure.” The wreck itself has become a haven for underwater life. Speaking to Live Science, the diver explained, “It is really thriving, covered with coral and giant fish.”