25 Aug 1942
While picking up survivors of the sinking of Trolla in thick fog astern of convoy ONS 122, HNoMS Potentilla obtained a radar contact approaching her in this vulnerable situation. At 05.21 hrs the corvette turned towards the contact and engaged U-174 with all weapons at a range of less than 300m (329 yds). One of five rounds from the 4in gun was observed to hit the base of the conning tower, and several hits by the AA guns were also observed. She had completely surprised the U-boat, but missed ramming her by a few metres, turning astern and coming up on her port side, then dropping five depth charges so close that the charge from the starboard thrower went over the diving U-boat to detonate on her starboard side, while the others landed to port. HNoMS Potentilla then dropped four depth charges ahead of the diving point, afterwards circling the area for an hour without obtaining an Asdic contact. The area was littered with wreckage and oil from convoy ships sunk, so no traces could be attributed to the U-boat. U-174 surfaced more than five hours later and surveyed the damage: several hits to the upper deck and conning tower, together with a leak in the galley and an untraceable leak that left a trail of oil behind the boat, forcing the commander to break off the patrol. (Sources: ADM reports, KTB U-174)

15 Dec 1942
An American Catalina flying boat from squadron VP 83 based at Natal, Brazil (Lt Wall) surprised the surfaced U-174 and dropped bombs before she dived, without result. (Sources: Blair, vol 2, page 55)

15 Dec 1942
Later in the day another Catalina from Squadron VP 83, this time piloted by Bertram J. Prueher, attacked a U-boat, probably U-174. U-174 left the area shortly afterwards due to lack of fuel. (Sources: Blair, vol 2, page 55)

3 recorded attacks on this boat.