Lieutenant Dan Daspit was exuberant.

The skipper was in command of USS Tinosa, which was on her second war patrol in late July of 1943. The submarine had been lurking the Japanese shipping routes from Borneo to Truk for a couple of weeks, and the crew finally spotted a thin trail of gray funnel smoke on the horizon. It was the Japanese tanker Tonan Maru No. 3.

Tinosa then approached her prey while submerged and fired four textbook shots. All the torpedoes ran true, and the crew eagerly waited to hear the unmistakable sound of the explosions. The expectations behind the Mark 14 torpedoes were enormous, as they were deemed the most advanced antiship weapons in the US inventory.

A few seconds later, the sonarman heard the projectiles’ thumps striking the tanker’s hull, and then, the unexpected happened…