The Baltic Sea, off Rügen, Saturday, 27 September 1941
Kapitänleutnant Günther Prien looked through the periscope of Unterseeboot 47 one last time to check the range and bearing to their target; the target ship Zahringen had not changed course and their firing solution was correct.
“Prepare to launch torpedoes… Three, two, one… Launch torpedo!” he ordered. The sound of the first tube firing echoed through the submarine. “Tube two – Launch torpedo!”
Through the periscope Prien watched the tracks of the torpedoes head toward the target ship… all appeared well, but suddenly the second torpedo’s track veered to starboard, and Prien lost sight of it. He turned to the men from the Bodenseewerke and cursed, “One of your toys has malfunctioned!”
The hydrophone officer reported that their first torpedo had locked on its proper target, the Zahringen; the other was circling, seeking a target.
“We have no idea Herr Kapitänleutnant,” said the one engineer. “We never had a malfunction in tests before.”
The hydrophone officer reported that the second torpedo had acquired a target – and was homing on the sound of the U-boat’s own engines.
“Emergency surface!” Prien ordered. “If we have to take damage I want to take it on the surface.”
The ballast tanks of the U-boat were blown and the boat shot towards the surface. Seconds later the misdirected torpedo struck them with a dull thunk, releasing a bright red marker dye. Prien noted the fact that his outer hull had been dented, but thankfully the practice torpedo had done no real damage.
With their boat now surfaced the crew tended to the damage inflicted on the U-47. The signals officer passed along a message from the Zahringen that it had taken a direct hit – red marker dye was being churned up in her wake. Prien turned to the men from the Bodenseewerke.
“Two torpedoes fired, and one malfunctioned,” he began.
“A fifty-percent success rate,” said the youngest of the three. “That is very good for the first operational test.”
Prien was unhappy that he had not been able to finish his comment. “Yes, and thankfully it was a test. You do realize that if that had been a real warhead we would likely be dead?”
To this the engineers had no answer; obviously, they needed to examine the torpedoes to see what had gone wrong. Much work would need to be done before their project was operational.