She commenced her training on 2 June 1943, making her first silent run at
Sønderborg, she remained with the
4th U-boat Flotilla (training) at
Stettin until 31 December 1943. She completed her training with a voyage from
Hela to
Swinemünde to practice A.A. cannon fire.
First patrol The boat was reassigned to the
10th U-boat Flotilla for combat duties in the Atlantic on 1 January 1944, departing
Kiel on 22 January 1944, with a three-day stopover at
Marvika in Norway. After forming up with the
Gruppe Igel 1 (Group Hedgehog) north-west of Scotland on 3 February 1944,
U-546 commenced a patrol in the North Atlantic with other boats to the west of Ireland on anti-convoy duties. At 12:29 on 16 February
U-546 reported she had been attacked by a British
Sunderland flying boat from
No. 201 Squadron RAF, killing one crewman. On 20 February 1944 she was again attacked by an aircraft. She returned to
Lorient for service and refit on 23 or 25 April 1944. The crew was given leave while the boat was overhauled and the
Schnorchel was fitted.
Second patrol Leaving her base again on 15 June 1944 for her second patrol to the African
Gold Coast, she was detected by a USN anti-submarine patrol, which begun to hunt her. She soon had to abort her patrol and was ordered to return to Germany after the
invasion of Normandy. On 18 June 1944
U-546 was attacked, again by a Sunderland, which was not equipped with radar. The boat then briefly returned to France on 22 June to replenish her cannon ammunition, sailing again on 25 June. On 20 July 1944 she was detected by USN surface ships forming the escort for an escort carrier;
U-546 fired a torpedo at the carrier, but missed and was subjected to three hours of depth charge attacks from the escort destroyers. She managed to escape this attack.
U-546 was then ordered to patrol a zone near
Cape Verde where she operated for about four weeks, attacking a convoy with a spread of three torpedoes, but scoring no hits. During the second patrol due to fuel shortages the captain achieved significant fuel saving and extended the cruise to 150 days (the boat's longest patrol), In mid-April the group was ordered to commence operations individually. On 23 April the submarine was spotted surfacing north-west of the Azores by aircraft from as part of
Operation Teardrop. The planes were looking for U-boats carrying
V-1 flying bombs and
V-2 rockets, which intelligence suggested were going to be used to attack American cities. Depth charges were dropped just after the boat submerged, but failed to damage her hull.
Sinking On 24 April 1945,
U-546 made contact with the
destroyer escort and proceeded to attack, firing a stern torpedo. The destroyer escort turned into the torpedo and was hit, which tore her hull apart and sent her down with heavy loss of life. The U-boat was in turn pursued by other destroyer escorts; , , , , , , , and .
Neunzer and conducted a search while
Pillsbury circled the area and
Flaherty picked up survivors.
Flaherty made contact in less than an hour and with
Pillsbury proceeded to attack. The U-boat went to . Contact was lost from 10:45 until 12:01 when
Varian,
Janssen and
Hubbard began another attack.
Neunzer got into the fight after several attacks by the other DE's, delivering a creeping attack with
Varian and
Hubbard while
Chatelain directed. Contact was lost once more at about 16:00, so
Chatelain and
Neunzer were ordered to return to the scouting line. The line was expanded, the ships began a sweep through the area, determined to prevent the submarine's escape.
Varian made contact once more at 17:31 and
Flaherty was ordered to attack. She fired at 18:10. Four minutes later a small oil slick began coming to the surface.
Flaherty made another
Hedgehog attack at 18:28, and at 18:38 the U-boat broke the surface. Every ship in the line within range began firing. At 18:44, after more than ten and a half hours of attacks,
U-546 rolled under and sank (in position , south-south-east of
Cape Farewell, Greenland). Her captain and most of her crew were rescued by US vessels, and taken to
Argentia Naval Station, Newfoundland. Eight of the surviving, captured crewmen of
U-546 were tortured by US military personnel. Historian Philip K. Lundeberg has written that the beating and torture of ''U-546's'' survivors was a singular atrocity motivated by the interrogators' need to quickly get information on what the U.S. believed were potential
cruise missile or
ballistic missile attacks on the continental US by German submarines. The USN eventually learned that no V-1/2 attacks from the U-boats were planned by the Kriegsmarine.
Wolfpacks U-546 took part in three
wolfpacks, namely: • Igel 1 (9 – 17 February 1944) • Hai 1 (17 – 22 February 1944) •
Seewolf (14 – 24 April 1945) ==Summary of raiding history==