Sunderland “A” of 423 Squadron attacked U-672 while on patrol in the North Atlantic. The U-boat was severely damaged but escaped. Narrative from Appendix 3 of Operations Record Book, 423 R.C.A.F. Squadron.

Short Sunderland “U” of 422 Squadron, similar to the one that attacked U-672. National Defence Image Library, PL 40993.

At 1339 hours on 24th April, 1944, Sunderland A/423 was in DR. position 30º44'N 18º40'W flying on course 180ºT (no drift) at 2100 feet when the captain saw visually a wake bearing 175ºT distant 16 miles (8 minutes flying time). Speed was increased to 140 kts [knots] while the second pilot confirmed with the binoculars that the wake was that of a U-Boat in position 50º36'N, 18º36'W (Cor) on course 180º speed 16 kts. Aircraft maintained course and height for about 8 miles when Captain made a slight turn to port preparatory to turning to starboard to take up a position to attack.

When the aircraft was abeam of the U-Boat and five miles distant, the latter commenced to make a tight turn to starboard with the object of always remaining stern-on to the aircraft. Simultaneously the U-Boat opened fire with medium flak which exploded with White puffs about 2½-3 miles short but was accurate for line. Shells were also observed to splash short into the sea. The form taken by the firing was a box barrage. No tracer was seen. The aircraft was dead astern of the U-Boat at this time. Aircraft continued to turn to starboard and when it was between U-Boat and the sun the U-Boat momentarily retarded its rate of turning and the aircraft commenced its run-in, being on course 340ºT, after having turned through 180º in manoeuvring for position. When 1,200 yards distant aircraft opened fire from four fixed nose guns and two front turret guns, firing a total of 1500-1600 rounds, with such effect that the U-Boat was silenced for the last 300 yards of the run-in. Up to this point the aircraft had received numerous hits but nevertheless the Captain pressed home his attack with the minimum of evasive action consisting only of slight diving turns.

At 1347 hours aircraft tracked right over the still surfaced U-Boat from starboard quarter to port bow, course of aircraft being 340ºT and of U-Boat 360ºT six Mk XI Torpex D.C.s [Depth Charges] set 25 feet spaced 60 feet were released from 50 feet. As the rear gunner, who had his guns fully depressed, saw the forward part of the U-Boat in his sights and pressed the trigger there was a violent explosion - estimated by S.I.O. [Section Intelligence Officer] from calculations made after tests with camera and bomb switch, to be of fourth D.C.

The force of this explosion was such as to throw up the entire moveable contents of the aircraft - floorboards, I.F.F. [Identify Friend/Foe] set, crockery, eggs and oven forming a new variety of omelet, on the edge of which the rear gunner was knocked unconscious and the W.O.M. [Wireless Operator] thrown from his perch in the astro-dome.

All electrical circuits became u/s. the R/T [Radio Transmitter] cable was severed, wing seams opened, and port flaps rendered u/s amongst other damage, but the principal damage was to the elevator which needed all the skill and strength of the Captain assisted by the Second Pilot to counteract. The aircraft being full tail heavy started to climb and although trimmed full nose heavy (14º) still required pressure on the controls. All crew were eventually stationed forward of the main spar to assist by their weight in maintaining trim.

Meanwhile, when the aircraft as 300 yards distant the front gunner saw approx. 70-100 feet astern of the U-Boat a brownish pool with blue smoke hanging above it.

While the aircraft was being got under control the rear gunner, who had regained consciousness, saw the U-Boat stern down and appearing to list, possibly caused buy its continuing the turn which it had commenced evasive action. This condition was confirmed by two of crew in port galley hatch and one in astro-dome.

At this point the aircraft had been got on to an even keel and having gained height to 600 feet a careful turn was made so as to track over the scene of the action. This turn, taking 2-3 minutes, prevented continued observation of the U-Boat and the above was the last that was seen of it.

When the aircraft arrived over the D.C. pool there was a patch of light blue oil 300 feet by 100 feet with tails or streaks 200 yards long pointing towards the D.C. pool, the patch being 400 yards north of the D.C. pool. No swirl, wake or wreckage was seen.

The aircraft, which had dropped a Marker Marine Mk. II at the time of attack, remained in the vicinity for 36 minutes, then dropped a Marker Marine Mk. III set for 2 hours delay and set course for base.