Lieutenant Commander Lawrence Randall “Dan” Daspit, captain of the U.S. submarine USS Tinosa (SS-283), was astounded at his luck. Framed in the periscope eyepiece was a 19,250-ton Japanese tanker, and it had no escort. The Tonan Maru No. 3 was making only 10 knots. It was a sitting duck.
Tinosa was on its second war patrol, having departed from
Midway on July 7, 1943, to prowl the Japanese sea lanes between Truk and Borneo. On the afternoon of July 24 Daspit, having been alerted by his surface-search radar, spotted a thin trail of gray funnel smoke on the horizon. He submerged and headed for the target. Once in range, he fired four Mark 14 torpedoes at the tanker. All four torpedoes ran true. Thirty seconds later, the sonarman heard four distinct “thumps” of the torpedoes striking the hull, but no explosions. The tanker turned away and increased speed.
Daspit surfaced and began the pursuit with his diesel engines. After a long nighttime chase, he was finally in position to try again. His torpedomen checked every fish to make sure they were working perfectly. Then, coming at the tanker from the starboard quarter, Daspit fired two more torpedoes. Both hit and detonated. The muted rumble echoed through Tinosa’s hull, eliciting cheers from her crew.
They had hit the tanker’s engine room. The vessel slowed to a stop.
Daspit took his time approaching the ship’s port side. He planned to fire one torpedo at a time from 1,000 yards, aimed to strike the tanker at the perfect 90-degree angle. The 680 pounds of high explosive in a Mark 14 would tear a huge hole in the hull. Two or three fish would send the vessel to the bottom. It appeared that the Tonan Maru was doomed.
At 9:30 a.m., fired the first torpedo. It ran straight and true, its wake a long, white trail aimed at the helpless ship. But the torpedo failed to explode. Daspit fired again.
