Operation OVERLORD was the supreme offensive action of the Western Allies in the war.
It could not have taken place without the Atlantic victory to which Coastal Command made such a magnificent contribution.
The victory so handsomely won had to stay won. Against such an enemy as Germany, only actual surrender could guarantee this, and surrender was still some two years away. When it arrived, it revealed how frighteningly close the battle had come to being lost again. But at the end of 1943 there was every reason for the Allies to feel pleased with themselves and their performance; it had been a record year for destruction of U-boats – 219, of which Coastal Command (and forces under its direct control) accounted for no fewer than 84. The crow was fighting the mole to some effect.
In 1944 the statistics of the war at sea show how well the work was kept up: a grand total of 1,045,629 tons of shipping sunk – a mere 13.4 per cent of the terrible total of 1942. Significantly, sinkings by U-boats fell to 773,327 tons (132 ships out of 205), and more significantly still, in the whole year sinkings by U-boats in the North Atlantic amounted to no more than 175,913 tons (31 ships). It was during this period, without doubt, that Ultra proved itself; from August 1943 onwards, the ability to read the U-boat signal traffic currently made possible interception of returning boats by aircraft and naval offensive groups, just when they believed themselves to be relatively safe. Ultra also permitted the destruction of the U-tankers (the “Milchcows”) with equal precision. It is remarkable indeed that in all this time B-Dienst, for all its brilliance, never diagnosed the fault. One reason must certainly be what has been called “trained incapacity”:
Their minds had been dragooned and regimented into the belief that Enigma was totally secure: therefore they were incapable of assessing objectively any indications that it had become insecure.
As Donald McLachlan succinctly puts it:
It is always difficult for experts to prove themselves wrong.
But Professor R. V. Jones reminds us that the blindness of B-Dienst was much increased by certain deception ploys practised against it; not least of these was the standard procedure of covering every Ultra-guided attack by ostentatious use of air patrols, so that a good reason for the ambush would readily suggest itself. Feints and decoys can be wearisome (and dangerous) work for those who have to carry them out; not least of Coastal Command’s contributions was the long haul of tiring and apparently unrewarded (certainly unexplained) hours of flying simply to register a presence. Theirs was that kind of war.
The technological see-saw continued almost to the end; new weapons and new tactics made constant appearances. On the Allied side it is worth noting the advent of three-centimetre radar (Spring 1944) and sonobuoys; the combination of these with homing torpedoes proved fatal to over-confident U-boats. But it was the Germans who made the real breakthrough in submarine warfare – as one might expect. All submarines launched during the two world wars were, in truth, incorrectly named; their true designation was “submersibles”. The true submarine, with unlimited underwater endurance and underwater speeds equivalent to those of surface ships, did not appear until the atomic-powered craft of the 1950s. But it was in 1943 and 1944 that large strides were made towards this kind of vessel.
The need for a new type of boat, with much increased performance under water, and much reduced surface time or none at all, probably requiring a new system of propulsion, was recognized. The eminent German scientist and maritime engineer, Dr Hellmuth Walter, was working on such a vessel, but progress was slow; as a stop-gap, to enable existing U-boats to remain submerged for longer periods, a pre-war Dutch device was introduced: the Schnorkel. This was an air pipe which could be extended above the surface when the U-boat was at periscope depth; it meant that “the air inside the boat could be kept fresh even though the rest of the craft was submerged; more important, a submarine could run virtually submerged on the diesel engines indefinitely, without the need to expend precious current from the batteries.” It had disadvantages: it limited the U-boat’s speed to six knots; it caused much discomfort to the crew in rough weather; it could still be detected, both by the eye and by radar, but obviously with much more difficulty than a fully surfaced boat or even a conning tower.
For all its limitations, however, the schnorkel was a large step in the right direction so far as the German Navy was concerned.
A trial installation was tested in the summer and autumn of 1943, and by mid-1944 some 30 U-boats had been fitted with the device; thereafter it became standard equipment and a great nuisance to the anti-submarine forces.
The real stride into the future, however, began at the same time as the adoption of the Schnorkel: a specification was finalized for a new kind of boat altogether, designated the Type XXI. This would have three times the battery capacity of a normal boat; its maximum underwater speed would be 18 knots (maintained for one and a half hours); it would be able to maintain 12–14 knots for 10 hours, or cruise at six knots for 48 hours – which meant a range of nearly 300 miles completely submerged. It would have to be a large boat – 1,500 tons, as compared with the 770 tons of the Type VII. The Navy placed orders for 290 Type XXI U-boats, expecting delivery of the whole number by February 1945. To expedite this programme, it was decided to pre-fabricate the boats in sections constructed in factories all over Germany; the completed sections were then to be moved to final assembly yards in Hamburg, Danzig and Bremen by canal – the only means by which such huge loads could be transported. Warned by Bomber Command’s devastating attacks on the port of Hamburg in July and August (when heavy damage was caused to the Blohm und Voss U-boat construction yards) Otto Merker, head of the shipbuilding office, ordered the construction of a bombproof assembly factory at Bremen. The Germans were by now “artists at ferroconcrete”; the Todt Organization began work on an assembly bunker, code-named Valentin,
with walls 10 to 15 feet thick, measuring 1,350 feet long and 320 feet wide, covering an area about twice that of the Houses of Parliament in London, with an inside headroom of 60 feet, the whole covered by a roof of reinforced concrete 22 feet thick; to enable the XXI boats to test their schnorkel equipment while inside the bunker, the water level at the outer end was to be dredged to 60 feet.
This massive structure was an even less promising target for bombers than the pens on the Biscay coast. However, there remained the canals, in particular the Dortmund-Ems, linking the Ruhr to the Ems River. On the night of September 23, 1944, Bomber Command (617 Squadron) attacked the aqueduct carrying this canal near Münster, wrecking it and causing a six-mile stretch to drain and bringing all traffic to a halt. When it was repaired in November, Bomber Command wrecked it again, and repeated the process twice more by the New Year. The Mittellands Canal, linking the Ems with Berlin, was similarly treated. The delivery programme of Type XXI U-boats naturally suffered, but it is yet another aspect of Germany’s amazing resilience (to which we shall return) that, even so, 90 Type XXI boats had been launched, of which 60 were in service, by the end of December. In addition, 31 of the smaller Type XXIII had been launched, and 23 were in service. Fortunately, none were operational. In the event, six Type XXIII boats became operational in February 1945, and they sank six ships without loss to themselves. The first operational Type XXI boat put to sea on April 30; it succeeded in evading a Royal Navy submarine hunting group without difficulty, but before it could launch a torpedo in anger the signal came from Grand Admiral Dönitz announcing Germany’s surrender, and ordering the U-boats to give themselves up in designated ports.
The end arrived none too soon in the maritime war:
after the war, trials established that even with the finest equipment available in 1945, against a schnorkel an aircraft radar search was on average only about 6 per cent efficient – that is to say, for every six schnorkel heads detected, a further ninety-four had come within radar range but had passed unnoticed in the general sea clutter … Thus by 1945 the wheel had turned full circle: having evolved from a blunt and ineffectual weapon into a deadly killer of submarines, at the end of the war the anti-submarine aircraft was – for want of an adequate method of long-range detection of submerged boats – almost back where it had started. The fast schnorkel submarine had emerged from the Second World War technically, if not militarily, triumphant.
What might have been, however alarming, in no way diminishes the quality of what was. Coastal Command’s achievement stands for all time: starting with just two kills in 1941, by the end of the war its own unaided efforts had accounted for 169 German U-boats out of 326 destroyed by shore-based aircraft alone. Expressing it somewhat differently, shore-based aircraft had accounted for 41.5 per cent of all kills, and of that number Coastal Command accounted for 51.8 per cent. In addition, another 40 kills were attributable either to US aircraft operating under Coastal Command control, or were shared with naval forces. The Command was also responsible for the sinking of four Italian boats (two in the Atlantic), with one shared.
For this, of course, there was a price to pay. In the final issue of Coastal Command Review in June 1945, it was stated that, in the course of the whole war, 1,511 aircraft of the Command had been lost by enemy action or were missing. Adding fatal crashes on return from operations, Hilary Saunders makes this 1,777. He also tells us that 5,866 pilots and crew (1,630 from the Dominions) were killed.
Slessor, writing in 1956, was convinced that
The crews of Coastal Command certainly did not get their meed of public recognition at the time; nor have they since …
For this he is much inclined to blame Churchill, and the section of Closing the Ring which deals with the Atlantic victory does, indeed, seem distinctly meagre and cursory by comparison with other passages. Yet, as we have seen, Slessor himself was not entirely guiltless in this connection. His own tour of duty at Northwood ended on January 20, 1944; he was a popular commander, a hard-hitting professional with a clear mind (except when clouded by dogma); above all he was a leader. He was fortunate in arriving when the Command was on the brink of its long-awaited triumph. His successor, Sholto Douglas, arrived – as was his unlucky habit – too late for the great days. Yet it is fair to say that under all its chiefs – Bowhill, Joubert, Slessor and Douglas – Coastal Command, in its long fight not just against the enemy, but against inadequate equipment, the Atlantic storms and the tedium of endless miles and endless hours of empty sea, construed once more beyond any chance of error the motto, “per ardua”.