Authors: Michael Gannon
The A.P. head was screwed into a steel tube four feet in length containing cordite that was ignited electrically. The tube and head traveled together, moved forward by the recoil action of gas escaping at high speed from the combustion of cordite in the rocket engine. When launched from an aircraft such as the Swordfish, flying at 120 knots, the rocket reached a maximum velocity of 1,600 feet per second after
1
½
seconds. There was no recoil, or “kick,” felt by the Swordfish, which could carry a load of eight R.P.s hanging from projector rails, four under each lower main plane. As engineered, the projectiles could be fired in four pairs or as a single salvo of eight. Trials conducted at the Aircraft and Armament Experimental Establishment at Boscombe Down indicated that upon striking a U-boat’s hull, the A.P. head fired from 400 yards or less would cause a 3-inch puncture. A perforation that large, it was thought, would prevent a surfaced boat from diving and a diving boat from resurfacing. The introduction of burning cordite into the U-boat’s interior was expected to delay a crew’s attempt to repair the hole and expel water by pumps. If repair could be effected, the U-boat at the very least would have to return to base.
Remarkably, the R.P. proved to have excellent underwater ballistics. Normally, the pilot’s aim should be taken at the base of the U-boat’s conning tower. Should the shot fall short and enter the water, and should the firing have been made from an optimum distance of 400 yards, at an angle of 20°, the rocket would travel submerged, reaching a depth of 13–15 feet, for a distance of 100 feet, and retain lethal penetrative power for 70 of those feet. If the angle of shot was less than 10°, however, the rocket on striking the water could be expected to ricochet.
Tactical advice given the first pilots to carry this weapon in May stressed the importance of making the final run in at 400 feet altitude, with slant attack angle on the U-boat of 20°, firing at 400 yards range. Attack should be made as nearly as possible dead on the beam to prevent glancing blows. Attacks should not be attempted when a diving U-boat had reached periscope depth or had completely disappeared. Once rockets had been fired, the pilot should break away at once to left or right, since if the rocket hit the U-boat it would throw up debris, and if it did not hit, but traveled underwater, one-third of R.P.s emerged from the sea at a steep angle, climbing to 200–300 feet.
94
Before a rocket projectile was fired in anger against a land target or against a merchant ship, Swordfish “B” of 819 Sqdn. embarked on
Archer
struck the first blow, while flying on Sunday, 23 May, in support of Convoy HX.239, about 750 miles west of Ireland. When
Archer
left port she carried the first three carrier aircraft to be fitted with RP. Two of them suffered damage landing in rough weather, however, with the result that “B,” piloted by Sub-Lt. Harry Horrocks, R.N.V.R., had sole honors when U-752 made the mistake of traveling surfaced on the port quarter of the convoy in full view of Horrocks and his two-man crew, who were at 1,500 feet 10 miles distant. The time of the sighting was 1015.
Horrocks climbed into cloud cover, where he stayed until he estimated that he was positioned on the U-boat’s beam. He then dived and sighted the enemy slightly on his port bow, range one mile. Deciding to fire in four pairs, Horrocks initiated the attack from 800 yards, twice the recommended range. The first pair fell 150 yards short. The second pair was ignited at the optimum 400 yards, but it, too, was short, by 30 yards. The surprised U-boat began a crash dive, and the third pair, from 300 yards, entered the water 10 feet short while the U-boat’s stern was still visible. One of these two rockets penetrated the pressure hull. The fourth pair, from 200 feet, cleanly hit the hull about 20 feet forward of the rudders.
The now-punctured boat immediately resurfaced and, after several futile attempts to dive again, circled on the surface while discharging heavy trails of diesel oil. When her crewmen manned the 20 mm flak, Horrocks called for assistance from a nearby fighter. Coming on the
scene in less than a minute, Martlet (Wildcat) “B” loosed off a long burst of 600 rounds at the conning tower that killed the Commander, Schroeter, and a midshipman, while sparing the II.W.O., who was standing alongside them. Below, the L.I. ordered the crew out and scuttled the boat. Both the L.I. and I.W.O. went down with her. Eleven survivors were picked up by a destroyer from HX.239's screen, and several more were later pulled from the water by another U-boat, U
-91.
Aboard
Archer
there was understandable elation in becoming the second escort carrier to bag a U-boat singlehandedly, and the first to get a kill with R.P. It was, states the official British Naval Aviation history, “shooting in the best traditions of the Wild West.'”
95
As stated in A Word to the Reader (page xv), the focus of this narrative has been on the major convoy battles and on Coastal Command’s Bay Offensive, both of which defined the German defeat in May. Still, it must be recognized that Allied operations against U-boats were occurring outside those two contexts throughout the month, and that eleven of those actions led to sinkings. Lest a narrative already heavily saturated with attack detail be further thus burdened, only the essential information about those sinkings is given below.
On 4 May, Coastal Command Liberator “P” of 86 Sqdn., while in 47°10
‘N,
22°57'W, on passage out to meet Convoy HX.236 northeast of the Azores, received an S/E (10-centimeter radar) contact, soon afterwards sighted a U-boat on the surface, and attacked it with four D/Cs. An oil patch and wood planking announced the result. Sunk with all hands was U-109 (Oblt.z.S Joachim Schramm).
96
On the nth, U
-528
(von Rabenau), last seen as a member of Group
Star
on 29 April (chapter 4), where she was damaged and forced back to base by the B7 escort of Convoy ONS.5, was proceeding home in 46°55'N, 14°44'W when she was discovered on the surface by Halifax “D” of 58 Sqdn., which was escorting Convoy OS.47 en route to Africa. Five D/Cs badly wounded the boat, which was then finished off by the sloop H.M.S.
Fleetwood.
and the corvette H.M.S.
Mignonette
from the convoy’s escort, which picked up fifteen survivors.
97
On 15 May, a Type IXC boat,
U-176
(Korv. Kapt. Reiner Dierksen),
was operating in Outer Seas northwest of Havana, Cuba, when she was sighted by a Vought-Sikorsky OS2U-3 Kingfisher observation plane from USN Patrol Squadron VP-62, which was escorting a two-ship convoy. When the U-boat dived, the pilot marked the swirl with a smoke bomb, then flew over the surface escorts, dipping his wings and directing the Cuban subchaser CS—13 to the scene. The Cuban vessel dropped a three-charge pattern that was followed by
four
explosions. There were no survivors.
98
Similarly, all hands were lost when the flush-deck destroyer U.S.S.
MacKenzie
(DD-175), escorting Convoy UGS.8 200 miles west northwest of the Madeira Islands, encountered and destroyed U
—182
(Kptlt. Nicolai Clausen). The well-proven boat, a type IXD
2
, was returning to base from patrols off Cape Town and Madagascar. There were no survivors. The date was 16 May.
99
The next day, at 0830, in the Outer Seas off southeast Brazil, U
-128
(Kptlt. Hermann Steinert) was sighted on the surface by a USN Martin PBM-3C Mariner flying boat (74-P-6) of Patrol Squadron 74 based in Natal and Aratu, Brazil. The U-boat dived, but only 15 seconds had elapsed before the PBM dropped six D/Cs ahead of the swirl. Forced by damage to surface three minutes later, the boat made a run for the Brazilian coast, but another PBM (74-P—5) came on the scene and further crippled the surfaced boat with six D/Cs. At about 0930 the U-boat’s bridge lookouts sighted the approach of destroyers U.S.S.
Moffett
(DD-362, Porter class) and
Jouett
(DD-396, Somers class), and Steinert ordered the crew off and the boat scuttled. Seven of the crew died during the attacks, fifty-one were rescued by
Moffett,
and four died aboard her.
100
On the same day, in the North Atlantic between the Shetlands and Iceland, Hudson “J” of 269 Sqdn. caught U-646 (Oblt.z.S. Heinrich Wulff) on the surface and released four D/Cs while the diving boat’s conning tower was still fully visible. One minute later a 100-foot-high cloud of gray smoke appeared over the D/C scum, followed 30 seconds later by oil and debris. There were no survivors.
101
The Type VIIC U
-414
(Oblt.z.S. Walter Huth), on her first patrol, broke through the Strait of Gibraltar and on the 21st was pursuing a convoy in the western Mediterranean when the spanking-new Benson class destroyer U.S.S.
Nields
(DD-616) destroyed her with D/Cs at 36°
OI’N,
oo°34'E. None of the crew survived.
Five days later, PBY-5A Catalina “F” of USN Patrol Squadron VP-84 from Fleet Air Base, Iceland, sighted a surfaced U-boat southeast of Iceland and attacked it while still surfaced with three 350-pound D/Cs dropped from 100 feet. The U-boat dived, and pilot Lt. R. C. Millard, U.S.N., making a second run, released a Mk.24 acoustic homing torpedo. Its hydrophones correctly fixed on the U-boat’s cavitation and brought oil and wreckage to the surface—FIDO’s second success of the month. The stern-punctured victim,
U-467
(Kptlt. Heinz Kummer), went down with all hands.
102
At 1356 on the same day, U-436 (Kptlt. Günther Seibicke) was submerged, returning from her third Atlantic patrol, when she was picked up on asdic by the frigate H.M.S.
Test,
part of the escort of a U.K. to Gibraltar special convoy, KX.10.
Test
made two D/C attacks, then lost the contact. The nearby corvette H.M.S.
Hyderabad
joined
Test
in a box search and at 1434 acquired a contact, which she attacked with a ten-pattern. Eighteen minutes later, having regained contact,
Hyderabad
dropped a second ten-pattern, which brought to the surface oil, large quantities of wood, a sou’wester, a glove, cigars, and a piece of human flesh. There were no survivors.
103
On the afternoon of the 28th, northeast of Valencia, Spain, in the Mediterranean, Hudson “M” of 608 Sqdn. based at Blida (ElBoulaï'da), Algeria, sighted and sank a U-boat with R.P. It was the first successful use of rockets by the RAF. The victim was U-755 (Kptlt. Walter Going), from which thirty-eight crewmen were lost. Nine survivors were picked up by the Spanish Navy and later repatriated to Germany.
104
At 2036 on the same day, while on passage out from Reykjavik to meet convoy HX.240 in the mid-Atlantic, Liberator “E” of 120 Sqdn. sighted U-304 (Koch), seen earlier in the battle for SC.130, and attacked the partially surfaced boat with four D/Cs. One minute later, an oil patch and wood wreckage appeared. All hands went down on this boat’s only combat patrol.
105
Even before that last date, Grand Admiral Dönitz must have felt like an infantry company commander whose position was being overrun by waves of enemy assault troops; for on the 24th day of the month he came, reluctantly, to the conclusion that the losses in May had “reached an impossible height.” Where “not long ago” one U-boat was lost for every 100,000 GRT sunk, which was an acceptable if not an ideal figure, now a boat was being lost for every 10,000 GRT. In an analysis prepared by Konteradmiral Godt and the BdU staff, the RAF was credited with playing a “decisive” role in bringing about that change in fortunes—attributing to the RAF not only the land-based aircraft that the U-boats were encountering but also the carrier aircraft, which were not in fact RAF but Fleet Air Arm (Naval Aviation). Dönitz concluded that, “The excessive losses and the lack of success in operations against the latest convoys now force us to take decisive measures until the boats are equipped again with better defense and attack weapons.”
The decisive measures were to
withdraw U-boats from the northern transatlantic convoy lanes
and transfer the main effort to the West African and Brazilian coasts, the Caribbean Basin, and the traffic between the United States and Gibraltar in the Central Atlantic. While reminding his boats in a “To All Commanders” signal that the North Atlantic remained the principal operational area, and that operations “must” be resumed there once new weapons were supplied the boats—he named an effective radar search receiver, the anti-escort acoustic homing torpedo (
Zaunkönig
), and the quadruple 20mm antiaircraft installations—for now, Dönitz stated, in “a temporary deviation from the former principles for the conduct of U-boat warfare,” the boats must in great part vacate the densest convoy lanes because, simply, he would “not allow the U-boats to be beaten at a time when their weapons are inferior.”
Of course, he added, the North Atlantic could not immediately or completely be denuded of boats, for a number of reasons. Boats already operating there did not have sufficient fuel to make the Outer Seas and return. It would take time to top them up, and it would be dangerous to bunch them at bases where, because of the limited number of bays in
the bombproof shelters, many boats would be exposed to air bombardment. In order to camouflage the general retirement, certain boats would be assigned to stay on Atlantic station and transmit dummy signals to simulate regular patrol line traffic. New boats just coming into Atlantic service from home waters would have to remain on station in the North Atlantic “in spite of the difficult conditions.” They would be expected to stand by until the next favorable conditions for attack, that is, the new moon, recurred, the next such period being the end of June. Wellproved, or veteran, boats would be assigned to support the newcomers at that date. In the meantime, Commanders must strive to maintain the good morale of their men in the face of these temporary expedients.
106
To all officers at sea Donitz sent an Order of the Day under the same 24 May date. Just the day before, he had signaled them that the development of new defenses against Allied radar and weaponry was receiving “maximum application at all our stations,” and that new technology should be ready shortly. The time until then, he told them, “must be passed with cunning and caution,” though “with your old inexorable severity in the battle itself.”
107
Now, on the 24th, he repeated the theme, more poignantly: