U 171– at the end of a successful combat patrol sunk by hitting a mine shortly prior arriving at Lorient
The long distance Type IX-C Kriegsmarine U-boat U 171 left Kiel, Germany for its first combat patrol under its Commanding Officer, Kapitänleutnant (= Lieutenant Commander) Günther Pfeffer. Following a short replenish-ment stop over for fuel at Kristiansand, Norway the boat departed for the Atlantic Ocean, to pass the narrow sea areas between the Orkneys, Shetlands and the Faroe Islands for the open Atlantic.
On 05 July U 171 met the “milkcow” U-boat U 460 under the command of Fregattenkapitän (= Commander) Friedrich Schäfer, right in the middle of the Atlantic Ocean in Naval Quadrant CC 3682, to be re-supplied. Within four hours and twenty minutes U 171 received from the replenishing U-boat 63 cubic meters of fuel, provisions for 24 days and 50 potassium cartridges, plus medical and a few other supply goods. After being replenished U 171 headed for the area of operation assigned in the Caribbean.
On 20 July the U-boat passed the Windward Passage between the Caribbean Islands of Cuba and Hispaniola and proceeded along the Mexican Peninsula of Yucatan, to arrive three days later at the area of operations ordered off the coast of Texas. On 26 July U 171 spotted a freighter off the US coast near Galveston and initiated an attack. Both torpedoes fired missed, the but one torpedo from the second salvo of two fired hit the 4.351 GRT Mexican vessel Oaxaca. The freighter made water fast and grounded at the shallow coastal waters. The Oaxaca had a cargo of print paper, soda and piece goods destined for Veracruz. Six sailors of the 45 men strong crew did not survive, the others were rescued.
Noteworthy, that the Oaxaca has been the former German merchant vessel Hameln, which was seized by Mexico on 01 April 1941. Following this first sinking U 171 continued operating more to the East in the sea areas before the Mississippi estuary. On 28 July the boat launched two torpedoes against the oiler City of Richmont, of which one detonated early, whereas the second one missed. Despite, Günther Pfeffer further pursued the oiled which, however, managed to escape U 171.
On 01 August a J4F “Widgeon” amphibious aircraft of USCG 212 Sqn was flying a recce mission across the Mississippi estuary, when suddenly pilot Henry Clark White and radio operator George Boggs spotted a German U-boat. It was U 171 the crew had spotted, which in turn has sighted the aircraft as well and initiated an emer-gency diving maneuver. The Americans dropped a 150 kg bomb into the wake water of the diving U-boat. Radio-man Boggs later stated to have seen a hit for sure to be followed by the sinking of the U-boat. The aircraft circled for another hour over the dropping zone of its bomb, and it detected some oil leaks, which substantiated the assumption of having successfully sunk a U-boat.
In fact, after the war the crew of the USCG aircraft was accredited the sinking of U-boat U 166, which had been operating off the Mississippi estuary at the same time. Only some 60 years later it came to light that U 166 was not sunk by an aircraft, rather the USN Antisubmarine Chaser PC-566 was the one responsible for the sinking – whereas the U 171, thought to be the one in question in the first place, was able to escape the attack from the air.
As it turned out, U 171 was successful in sinking the 6.779 GRT US oiler R.M. Parker Jr. on 13 August before the Mississippi estuary. Only one of the torpedoes fired hit, the second missed. The Commanding Officer launched further four “coup de grâce” torpedoes against the oiler, with three of them hitting. When U 171 departed, the oiler had begun sinking quickly, albeit the water depth was just 35 meters at the scene, why in the end the bow section of the oiler continued to raise above the water line. The R.M. Parker Jr. was sailing in ballast from Baltimore to Port Arthur. The crew of 44 could be rescued entirely. Since Günther Pfeffer evaluated the sea areas before the Mississippi estuary and off Galveston as too shallow, and because the surveillance from the air during daylight became more and more dense, he decided to change his area of operations to the Mexican coast near Tampico.
On 04 September U 171 fired a salvo of two torpedoes against an oiler, which the vessel managed to evade. The second salvo of two fired from the rear torpedo tubes missed. Another time a salvo of two was fired – and again all torpedoes missed. After re-loading torpedoes Günther Pfeffer fired another torpedo from one of the rear tubes – this time the oiler was hit, which now lost speed quickly. However, it took further three “coup de grâce” torpedoes to finally sink the Mexican 6.511 GRT Amatlan. 10 of the 34 men strong crew did not survive the attack. The Amatlan was enroute to Tampico when she ran into U 171´s torpedoes.
Noteworthy, that 10 torpedoes were used in the end to eventually sink the oiler, with six of them clear misses. On 05 September U 171 commenced its return leg through the Mona Passage, with just two torpedoes left on board. During its homebound voyage it met the U-boat replenishment U-boat U 461 under the command of Kapitänleutnant Wolf-Harro Stiebler in mid-Atlantic. U 171 received 23,5 cubicmeters of fuel and provisions for three weeks, before it headed for Lorient, France. In early October 1942 it passed through the Gulf of Biscay and was on 09 October about 6 hours before estimated time of arrival at Lorient.
The further events leading to the loss of U 171 are taken from the report of the Commanding Officer Günther Pfeffer.
According to my last orders I had to be at rendevouz point “Lucie 2” at 16.00 hrs on 09 October, to be picked up by the escort. I did not have any exact reckoning for seven days and I got the coastline in sight at about 11.47 hrs.
At about 13.00 hrs I had a new and now assured fix based on terrestrial navigation and previous morse code message traffic with a coastal patrol boat. This message traffic revealed that the boat was not my escort assigned, but the true escort was on its way. Already for about an hour, up to five German aircraft could be seen at the horizon at some distance to the boat, among others a “Ju-52” minesweeping aircraft. The latter passed me several times at about 50 meters distance. Any diving at the water depths published was out of the question to me. I ordered the conning tower to prepare for cruising at surface and authorized four men to come up initially, later even more. When I was reaching rendevouz point “Lucie 2” according to my dead reckoning I decided to stay close until the escort would pick me up, doing zig zagging courses with half speed ahead. At about 13.40 hrs I turned port to heading 280 degrees with slow speed.
Shortly after making the course selected a detonation occurred in the forebody, right after the “Ju-52” had passed us at close distance. I estimated this to be a mine hit and ordered: “Both engines stop!” At first I thought to be able to keep the U-boat above water, but my order to stop engines apparently had not made it to the engine room. I could hear the diesel engines still running. When I realized the U-boat taking water I ordered: “All men to abandon ship!”. Soon after I shouted: “All men to jump over board!”.
I could hear the Chief Engineer Kapitänleutnant (Ing) Otto Dingeldein calling down from the conning tower: “Life vests up!” Seconds later he repeated his call, to be followed by his order “All men over board!” At the same time I saw one of the hatch covers of a bow torpedo tube open with two men stuck in it. I then shouted several times: “Shut the hatch cover!” supporting it by resolute sweep of my hands.
The U-boat became bow-heavy fast, the hatch cover was shut and the boat sank under the water surface. I did not shut the hatch cover in the conning tower, since men were still coming out. When the forward edge of the conning tower did undercut the water surface I also decided to jump over board. The boat´s stern was rising up high above the water and I still could hear the engines running. When I came back to the water surface after I had left the boat, I could not see the boat any longer. I tried best as I could to remind all men in the water to stay together supporting any rescue operation. We then started to swim towards the Ile de Croix as proposed by the First Watch Officer Albert Kneip. I estimated about an hour later I was picked up by a vessel, it was the blockade breaking patrol boat 134 Falke.
30 men from U 171 were rescued by the Falke and other coastal patrol boats, one man was picked up already dead. But, 21 men were missing, with two of them being spotted swimming in the water at some time.
Another report by ensign Kurt Lau, who stayed in the U-boat for a longer time.
We just had passed the dangerous Gulf of Biscay without any enemy encounter. At noon on 09 October U 171 had reached the rendevouz point for pick up by the es-cort about 50 nm off Lorient. Since no escort was arriving to support U 171´s safe passage to Lorient, the Commanding Officer decided to proceed without escort. At about 13.40 hrs the U-boat hit a mag-netic mine within sight of the Isle de Croix off Lorient.
The degaussing situation of the U-boat had become ineffective due to the 16 weeks at sea. The boat sank within a minute at about 40 meters water depth. At this moment, there were roughly 20 men at the conning tower, which had been ordered to upper deck by Kapitänleutnant Pfeffer because of the mine threat. He had also ordered to man the anti aircraft gun given the air theat.
When the mine detonated, 17 men in the diesel and electric engine rooms died. As the diesel engine was still running when the sinking U-boat hull came under water the fresh air was sucked out of the diesel and electric engine room as well as from the rear crew compartment. All comrades were dead instantly. Some mechanic sailor in the central control room had managed to shut the valve to control the exhaust and supply air, otherwise there would not have been any survivors left in the central control room and the forward compartments of the boat. There were 16 survivors in the forebody of the boat. All had activated their emergency rescue breathing apparatus, except three men. Chloric gas from the forward battery compartment made breathing difficult for the men.
Roughly after an hour the U-boat´s forebody was flooded to an extent allowing pressure compensation. Since the hatch covers of the torpedo tubes ware jamming, an exit was possible through the hatch for torpedo transfers into the U-boat only. Able Seaman (Engines) Sauter heaved up the hatch and managed to open it. The air escaping from the inner boat wrenched the hatch open, but the water flooding in slammed it back to closing condition. This went on until the last air had escaped the inner boat. Then, the men left the U 171 resting on the bottom of the sea, three of them without any breathing apparatus.
One sailor did remain in the boat for unknown reasons. One man died after surfacing having experienced potassium cauterization from water penetration to the breathing apparatus. Further three sailors were washed ashore dead three days later.
When the 11 survivors surfaced three coastal patrol boats and the blockade breaking patrol boat 134 Falke were at the scene of the sinking of U 171 and had lowered their life boats for rescue purposes.
The Commanding Officer and the men, which were on the upper deck at the time of the mine explosion and had drifted helpless in the water after the sinking of U 171, had been picked up already from the sea by the rescue forces. The majority of survivors from the 52 men strong crew of U 171 formed the new crew of U 170, which would be commissioned on 19 January 1943 at the Seebeck shipyard at Geestemünde (today: Bremerhaven).
Until today U 171 is laying about 50 nm off Lorient at position 47° 39,5′ N and 03° 34,8′ W in the former Naval Quadrant BF 6173. The central control compartment and the aft section of the U-boat with the diesel and electric engine room as well as the rear crew compartment of U 171 lies almost intact at the bottom of the sea at about 40 meters water depth. The forebody of the hull of U 171 had been destroyed by blasting operations of the French Navy to de-arm the torpedo load still on board. The last of such operation was executed on 10 January 1995.
Text: Hans-Joachim Röll, pictures: German U-boat Museum