Flak U-boats
On 31 August 1942, U-256 was on her first cruise and sailing from Kiel to proceed to Lorient via the North Atlantic when she was attacked by a Whitley of 502 Squadron. The boat was so badly damaged that she was almost scrapped until a decision was made to convert her into a U-flak boat.
The U-flak boats were four of the type VIIC boats (U-441, U-256, U-621 and U-953) modified to simply act as surface escorts for incoming and outgoing attack U-boats operating from the French Atlantic bases. They had greatly increased anti-aircraft firepower and were purely intended to lure aircraft into a trap.
Three more U-boats were allocated as additional U-flak boats (U-211, U-263 and U-271) but were never completed in this configuration and returned to duty as standard VIIC attack boats.
The modifications took place in 1943 and initially had some successes against surprised RAF aircraft. Dönitz initially believed these boats had potential, although the RAF soon developed countermeasures while surface hunters were called in to assist the aircraft. As a result, the boats configured as U-flak boats were withdrawn and converted back into fighting vessels. However, many boats carried enhanced anti-aircraft armament, including additional guns installed forward of the bridge. These should not be confused with dedicated U-flak boats.
Although U-256 was the first boat converted into a U-flak, the work was delayed and on 16 April 1943 it was decided to convert U-441 in the same manner. Flakvierling mounts (20 mm quadruple sets) and the first experimental 37 mm automatic gun were installed on U-441, along with a battery of 86 mm line-carrying anti-aircraft rockets. However, the latter system proved impractical.
On some U-flak boats, two additional single 20 mm guns were carried. The fuel capacity on these boats was limited solely to Bay of Biscay operations and only five torpedoes were carried (these for self-defence) because extra accommodation was required for additional crew members to man the Flak guns.
The U-621 was converted into U-flak in June 1943 after being damaged on her fourth cruise by a Liberator of 224 Squadron on 31 May that year. U-621 as a U-flak sailed on 29 August 1943, but scored no success on this her fifth cruise. After reverting to ‘normal’ flak armament and becoming a standard attack U-boat again, she was damaged on her sixth cruise on 13 January 1944 by a B-24 Liberator of 59 Squadron.
The effectiveness of the improved anti-aircraft weaponry on the U-flak boats, and the scheme itself, had generally failed to live up to expectations with just the standard defensive armament on attack U-boats proving every bit as dangerous for Allied aircrews.
tower and bullets were seen passing just above port wing. Aircraft ‘B’ immediately returned fire with a long burst of cannon fire from 200 ft. U-boat was now also firing with heavy gun forward of conning tower and pilot saw something approximately the size of a cricket ball pass over the cockpit. Aircraft ‘V’ then came in to attack, firing a long burst of cannon fire. Hits were seen to register on the conning tower. U-boat was now firing continuously, and aircraft had to break away and take evasive action. Aircraft ‘A’ now came in and followed up with an attack by cannon fire. These shots were first seen to fall short but as aircraft approached shells were seen to strike conning tower. U-boat now commenced to take evasive action, zigzagging violently and firing meanwhile. All three aircraft repeated their attacks, and it was noticed that nearly all the 18 people originally seen on the deck had disappeared; one man was seen in the water and another laying on the deck. All fire from the U-boat had now ceased so the
Beaufighters were able to press home their attacks from a much lower level and as aircraft ‘S’ attacked the third time, an explosion was seen just aft of the conning tower. A subsequent attack on the same spot produced a much larger explosion...”
The Beaufighters continued attacking for another punishing 15 minutes, until the U-boat finally submerged. It must have been a punishing and terrifying ordeal for the men on U-441 who had valiantly stayed on the surface to follow Donitz’s order to ‘fight it out.’ In all, 10 men had been killed and 13 wounded including all the officers - apart from the doctor (Note: due to increasing injuries because of air attacks, from the beginning of July 1943, 50% of U-boats carried a doctor) who took command and headed U-441 back to Brest where it finally docked the following day.
It was now clear that the ‘Flak Trap’ U-boats were not the solution and U-441 (and U-256) was converted back to be a Type VIIC by December 1943, only to be sunk by aircraft in the English Channel in June 1944.
A BLOODY SUMMER
In summary, May 1943 had seen 39 U-boats lost on operations, of which 22 can be attributed to aircraft. This should be balanced against the 11 aircraft either shot down or badly damaged by U-boats that month. June 1943 saw another nine aircraft shot down or damaged, but 17 U-boats were lost and again 11 of them fell victim to aircraft. The month also saw aircraft from American escort carriers becoming involved, in particular the USS Bogue and her aircraft from VC-9. One VC-9 TBM Avengerpilot,lieutenant(jg)ws“munk”fowler,had the misfortune to have his aircraft damaged attacking U-641, commanded by Kpt.lt Horst Rendtel, south-west of the Azores on 4 June. Four days later, the same again happened while he was attacking U-758 commanded by Kpt.lt Helmut Manseck; both U-boats were damaged.
July 1943 would see a similar pattern, but this time combats were also occurring off the Brazilian coast and in the Caribbean. Again, 13 aircraft would be shot down or damaged attacking U-boats. For the Germans, this would be the bloodiest month yet with 37 submarines lost and an astounding 31 of these being attributed to aircraft. This forced the BDU to issue the following order on 2 August 1943:
“Enemy air and surface craft activity in Biscay is at present very strong and effective and losses have been heavy during the last days. U-68, U-123, U-505, U-523, which have only been at sea a short time, have therefore been ordered to return to their ports.
“It has also turned out that boats proceeding in groups are sometimes completely destroyed after being detected by aircraft or surface vessels which must be attributed to large numbers of anti-submarine forces working in good cooperation. Orders have therefore been given for the immediate dispersal of all groups on passage. Boats are to proceed alone, independently of the courses ordered.”
The first eleven days of August, however, still saw 12 aircraft damaged or shot down. Then, very little occurred until 6 September. However, the last recorded combat of the month had seen one of the most notable U-boat versus aircraft battles and resulted in the pilot involved being awarded a posthumous Victoria Cross on the recommendation of a U-boat captain.
New Zealander Flying Officer Lloyd Trigg, who had only recently been awarded a DFC, took off from Rufisque, near Dakar in Senegal, at 07.20 hrs on 11 August in a B-24 Liberator with a crew of seven. They were to undertake an anti-submarine patrol and the 200 Squadron Operations Record book recorded what happened:
“At 11 00 hrs was diverted to hunt for a U-boat which had previously been attacked by a Catalina. U-boat was found and attacked after gunfire had severely damaged the aircraft and set it on fire. The attack was a complete success, and the destruction of the U-boat was confirmed by some of its survivors who were also the sole remaining witnesses of the Liberator’s crash which occurred immediately after the attack with, we regret to record, the loss of the whole crew. Aircraft on Air Sea Rescue sorties discovered the remaining members of the U-boat’s crew in one of the Liberator’s dinghies.”
Trigg had attacked U-468, commanded by Oblt.z.s Klemens Schamong (which had set sail from La Pallice on 7 July) and managed to drop six depth charges - two
of which severely damaged the stern of the U-boat which sank soon afterwards. Of its crew of 51, less than half managed to abandon her - although only seven, including the captain, survived.
At 14.51 hrs on 12 August, a dinghy was sighted by a Sunderland of 204 Squadron flown by Flight Sergeant Charles Watkinson and presumed to contain the seven crew of B-24.
Then, at 06.30 hrs the following day, Flight Lieutenant John Pare, also of 204 Squadron, directed HMS Clarkia to pick up the dinghy when its occupants were found to the survivors of U-468 in one of the Liberator’s dinghies. It was only now that what had happened became clear:
“The Liberator was heavily hit and burst into flames during run-in, but nevertheless completed an accurate attack before diving into the sea at over 220 knots. U-boat captain and officers amongst survivors very impressed by coolness and courage displayed by doomed bomber’s crew.”
It was testimony which resulted in the award of the Victoria Cross to Lloyd Trigg on 2 November 1943, the lucky survivors of U-468 having been fortunate enough to make their way to the inflated dinghy of Trigg’s aircraft which had bobbed to the surface as the stricken Liberator plunged beneath the waves.
PAINFUL STING
The remainder of 1943 would be much quieter in respect of battles between U-boats and aircraft with four aircraft lost and damaged in September and five each in October and November 1943. Things were made more difficult for the U-boat crews when, from 8 October 1943, Portugal allowed the Allies to operate anti-submarine missions from Lagens airfield in the Azores meaning it was getting much harder for the U-boats to remain undetected.
The last recorded aircraft losses of the year came on 22 December 1943 when U-1062, a Type VIIF torpedo transport U-boat commanded by Oblt.z.s Karl Albrecht, was attacked by Beaufighters of 144 and 404 Squadrons off Egersund, Norway. The U-boat, together with minesweeper M-489, accounted for two aircraft of 404 Squadron, flown by Flying Officer Ian Gillespie and Flight Lietenant Roy Munro; all four crew members were killed. The U-boat was damaged with one crewman killed and three wounded with one more wounded on the minesweeper. On 30 September 1944,
having been discovered by aircraft, U-1062 would be sunk by USS Fessenden off the Cape Verde Islands; Karl Albrecht and all his crew were lost.
As seen in the accompanying table, the cost of aircraft lost to U-boats was considerable and saw no less than 67 Allied aircraft claimed as destroyed. Conversely, the losses of U-boats to aircraft were grievous; in total, 249 sunk by air attacks throughout the war. All told, it was a bloody and brutal struggle, and aside from 1943 (the focus of this article) at least five Allied aircraft were lost to U-boats in 1942 and another 35 in 1944.
Attacking U-boats from the air, and the engaging of Allied aircraft from U-boats, was a deadly business; the relative proliferation of gallantry awards evidence enough of the courage displayed by both sides in this bloody confrontation. Such awards included Knight’s Crosses and Iron Crosses, with many gallantry awards to aircrew on the Allied side. Included in the latter were no less than three Victoria Crosses*.
The sting from U-boat flak defences had been painful, albeit that the intended ‘sting’ of the dedicated U-flak boats had been rather less dramatic than Dönitz had hoped and intended.