A Piece of a Phantom: How a WWII Submarine Restoration Uncovered a Relic from a Lost Sister Ship

When restorers in Sturgeon Bay, Wisconsin, began work on the historic World War II submarine USS Silversides, they expected to clean off invasive mussels, repair aging steel, and give the vessel a fresh coat of paint. They did not expect to uncover a ghost from the Pacific theater.

Tucked inside the 312-foot vessel's ballast system, workers discovered a metal flood valve stamped with an unexpected designation:

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The component wasn't meant for the Silversides at all. It belonged to its sister ship, the USS Trigger—a legendary submarine that vanished in the East China Sea in March 1945.

The Mystery of the Swapped Valve

The discovery raises an intriguing mystery: how did a starboard-side ballast valve intended for the Trigger end up installed on the port side of the Silversides?

According to military history experts and descendants of the crew, the answer lies in the high-pressure environment of wartime shipbuilding. Both submarines were constructed side-by-side at California's Mare Island Navy Yard during the early days of World War II. In the rush to launch vessels after the attack on Pearl Harbor, shipyard workers frequently swapped parts between adjacent hulls to keep production moving.

For reasons lost to time, this specific flood valve, a hinged cap used to manage seawater levels in ballast tanks, was bolted into the Silversides, where it remained hidden for more than eight decades.

Two Ships, Two Very Different Fates

While both Gato-class submarines served with distinction in the Pacific, their eventual fates could not have been more different:

● USS Silversides (SS-236): Sunk at least 23 enemy vessels during 14 war patrols, making it one of the most successful American submarines of WWII. Decommissioned after the war, it became a floating museum ship in Muskegon, Michigan, in 1987.

● USS Trigger (SS-237): Credited with sinking 27 enemy ships and earning 11 battle stars, the Trigger was lost with all 89 crew members aboard on March 28, 1945, following an intense Japanese air and sea attack. Chillingly, the Silversides was operating nearby at the time and reported hearing the distant bombardment that sank her sister ship.

Preserving a Sacred Artifact

Because the Trigger rests at the bottom of the ocean, museum leaders believe this newly identified valve may be the only surviving physical component of the lost vessel anywhere in the world.

The USS Silversides Submarine Museum plans to carefully remove, restore, and display the valve as a dedicated tribute to the Trigger and the 89 sailors who went down with her.

This article was adapted from reporting originally published by Smithsonian Magazine.