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The War Below title block

The following is an excerpt from Operation Storm: Japan’s Top Secret Submarines and Its Plan to Change the Course of World War II. Operation Storm tells the true but little known story of the USS Segundo (SS 398), a Balao-class submarine, and her hunt for the I-401, a giant, underwater aircraft carrier purpose-built by Japan to launch a surprise attack against New York City and Washington, DC as a follow-up to Pearl Harbor.

By John J. Geoghegan

Between January and March 1945, almost 70 percent of ComSubPac war patrols mounted from Pearl Harbor returned without sinking a single enemy ship. Nevertheless, when the crew of the USS Segundo (SS 398) departed on their second war patrol, they were hungry for enemy contact.

Lt. Commander James D. Fulp, Jr. was the Segundo’s first Commanding Officer. Fulp had been with the Balao-class fleet boat since before her commissioning in Portsmouth Navy Yard in May 1944. The 34 year old native from Greenwood, South Carolina was an experienced submariner. He’d been Executive Officer aboard the USS Sargo (SS 188) when the war started, and had eight war patrols under his belt. The Segundo was his first command, however, and things had gotten off to a shaky start.

The Segundo had been traveling on the surface in the Surigao strait when two friendly aircraft appeared out of nowhere and strafed her. Three quarters of the way through their deployment, a Japanese aircraft dropped two bombs on them. The Segundo only had a few inches of water overhead when the first bomb struck. A loud explosion rocked the sub quickly followed by a second blast. Had they been depth charges instead of bombs, the damage could have proved fatal. As it was, the explosions damaged the Segundo’s deck gun, blew off one of her four engine exhaust mufflers, and broke the foundations mounts on the generator that powered her torpedo data computer.

Worse, they had trouble finding targets. The Segundo was patrolling in support of the Palau invasion, but since the IJN didn’t oppose the American landing, Fulp had nothing to shoot at. As one officer put it, “We were there—it was the enemy that didn’t show up.”

After a few weeks at Majuro rest camp, the Segundo joined “Roy’s Rangers,” a three sub wolf pack with orders to patrol the Luzon strait. Fulp had multiple ship contacts early in the second patrol, but December was typhoon season and heavy seas so hampered sub operations he couldn’t launch any attacks.

Finally, on the evening of December 6, the lead sub in Fulp’s wolf pack, the USS Trepang (SS 412), spotted seven Japanese merchant ships and three escorts. It was the biggest shooting gallery Fulp had ever seen and a happy end to what seemed like a very long drought.

Conditions were poor for a surface attack, but Fulp chanced it anyway. He’d be damned if he let the Trepang’s commander (known as the “praying skipper” for his religious beliefs) steal all his glory.
Using the dark background of Luzon for cover, Fulp crept along the surface. But as gale force winds whipped the sea into a frenzy, what had begun as an advantage soon turned against him. Fulp managed to close in on the convoy without being spotted, but conditions were so rough he worried a surface-fired torpedo wouldn’t run true. He also had to be careful not to sink one of his own subs—always a danger when operating in such close proximity.

Picking what appeared to be a troop transport, Fulp ordered the torpedo gyros set nearly to zero and launched six Mark 18s from the Segundo’s bow tubes. Given the storm tossed seas, it was a wonder the torpedoes ran straight. A few minutes later the first of three fish slammed into the transport’s engine room. A massive eruption of water, flame, and molten metal leapt into the sky followed by two more explosions. As the ship lay smoldering, her escort began circling like a calf around its wounded mother.

Confident the ship was disabled, Fulp took the opportunity to attack a second vessel. Using the cover of darkness, he wove between two escorts, one of which was so close she was only 400 yards away. It was an audacious move that left Fulp’s officers wide-eyed in astonishment. One of the defenders was the Kuretake. More than 20 years old, she was hardly a state-of-the-art destroyer. But she was accompanied by the CH-33, a modern Japanese sub chaser. Either ship could have had radar, but Fulp wasn’t deterred one bit.

After sailing through the defense perimeter, Fulp ordered engines to one-third to give the torpedo room time to reload. When all six tubes were ready, he maneuvered the Segundo into firing position and closed in for the attack.

Most World War II subs fired from a range of 1,800 to 2,000 yards, but Fulp had such bad experience with navy torpedoes, he didn’t trust them. On the Sargo’s first war patrol, he’d fired eleven Mark 14s, some at point blank range, and none had detonated. Torpedo failure plagued the Sargo’s next six patrols, which was particularly frustrating since it was the early days of war. By this point, Fulp was eager to make up for his misses.

While Fulp conducted his attack approach, Ensign Rodney L. Johnson operated the Segundo’s torpedo data computer (TDC) in the conning tower.

Ensign Johnson was new to the sub and hadn’t much experience. He had a good idea what a comfortable distance for an attack was though. An overcast night might have been ideal for up close and personal fighting, but once the Segundo closed to within 1,800 yards, Johnson’s confidence began to slip.

“Fifteen hundred yards, captain.”

“Proceed,” Fulp replied.

“Thirteen hundred.”


“Twelve hundred.”

Johnson’s voice betrayed his concern. Fulp remained unmoved, however. As they passed the 1,000 yard mark, Johnson protested they were nearly on top of the enemy.

“We’re gonna get close enough to throw stones at ‘em,” Fulp responded.

The Segundo finally fired at 900 yards. Keeping the spread small Fulp launched three torpedoes at least two of which hit home. The target wasn’t an ordinary freighter though; she was a giant Japanese ammunition ship.

The first explosion was so powerful, it knocked the Segundo’s chief torpedoman out of the conning tower down into the control room. When wreckage began raining onto the deck, one of the Segundo’s lookouts shouted: “Oh, my god, they’re firing at us!”

But the Japanese ammunition ship was too busy disintegrating to return fire.

Since water conducts sound faster than air, the experienced hands inside the sub knew what they were hearing.

“Ammunition ship,” one of them said. Seconds later the smell of cordite wafted in through the bridge hatch.

The explosions’ concussions were so immense, those on deck had to grab hold of something to keep from falling. When the heat wave reached their faces, it felt like their eyebrows were being singed right off.

As ammunition aboard the Japanese ship continued to explode, bright yellow flames lit up the night and tracer ammo arced across the sky. Strangely, the ship kept plowing a path through the sea even as she was being ripped apart. Then in an instant she was gone.

A sub’s patrol report is not known for exaggeration, yet the Segundo’s entry described, “the quickest…most devastating explosion imaginable (tore the ship apart)…it just did not seem possible that anything could be obliterated so instantaneously.”

Indeed it was remarkable that so large a ship could vanish into thin air. Even the Segundo’s radarman did a double take when the ship disappeared from his screen. The only thing left after one last massive explosion was the ship’s outline burned into the retina of the Segundo’s deck watch.

Fulp sank at least two and perhaps as many as three ships that night. He would have sunk more, too, if the weather hadn’t proven a far worse enemy than the Japanese.

For his courageous actions taking on the enemy convoy Fulp was put in the for the Navy Cross. The recommendation stated: “the fighting spirit and exceptional skill displayed by the Commanding Officer…was particularly outstanding and merits special recognition.”

Fulp didn’t receive the Navy Cross, however. There was too much confusion over who sunk what ships. In its place, he was awarded the Silver Star for valor, no small consolation given it’s the U.S. military’s third-highest decoration. It was an important acknowledgement of what he and his crew had accomplished.

All signs may have pointed to the war winding down, but as far as the Segundo’s new skipper was concerned, the Segundo’s fight had just begun.

John J. Geoghegan specializes in reporting on unusual inventions that fail to succeed in the marketplace despite their innovative nature. He currently serves as the Executive Director of The SILOE Research Institute’s Archival Division.