Engineers of Victory: The Problem Solvers Who Turned the Tide in the Second World War (12 page)

Not quite. We should not underestimate the extraordinarily important role of the intelligence war that was fought between the Axis powers and the Grand Alliance, but we must recognize that, operationally, Ultra could do only so much, and so we should not overestimate it, either. Depending on each side’s skills in concealing their own messages and reading those of the enemy, code breaking offered vital information that permitted the pre-positioning of forces for an impending battle. Both the Germans and the Allies benefited greatly from being able to read each other’s messages. Even if a decryption system worked imperfectly, a one-eyed man has an inestimable advantage if his opponent is blind. In 1942, it is true, the British lost their capacity to read Doenitz’s messages (or at least they took much longer to decrypt), whereas B-Dienst was providing the grand admiral with virtually immediate information about the Allied convoys; in the grim months of late 1942 and early 1943, that meant a lot.

But what if the convoys were better protected
and
the British could see as well as the Germans? Then things were greatly different. Consider, for example, the situation during mid-May 1943 in which each side was rather smartly reading the other’s traffic and sending the new intelligence to its forces at sea. By the time of the great battles (May 7–14) around convoys HX 237 and SC 129, the intelligence war had reached a remarkable level of sophistication, of point and counterpoint, so that neither side had the lead for very long. The same was true a week later with regard to the fighting that surrounded convoy HX 239, coming from Halifax to the Clyde. First, B-Dienst detected the location and course of this large group of merchantmen. Shortly afterward, the British cryptographers read Doenitz’s Shark instructions for a wolf pack ambush, so Western Approaches Command ordered the
convoys to alter course. But B-Dienst then read those signals and redirected the U-boat lines—no fewer than twenty-two submarines—to attacking positions. Unfortunately for the U-boats, however, at that point they met the massed forces of Allied air- and sea power over the Atlantic. The new escort carrier USS
Bogue
destroyed U 569, while HMS
Archer
’s aircraft, now fitted with rockets, sank U 752. No merchant ships were lost.
³⁹
The plain fact was that Ultra assisted in but could never win the hard-fought convoy battles. When the British decision was made to fight the convoys through the U-boat lines, victory went to the side with the smartest and most powerful weaponry, not the one with the better decrypts.

We can now understand how these great advances in the Allied systems of detection and destruction interacted with the two other factors mentioned above: numbers and morale. When, in mid-March 1943, HMS
Volunteer
was the only escorting warship with convoy HX 229 to possess HF-DF, and when its radio operators had time either for detection of U-boats or for receipt of Admiralty orders but not both, its potential was limited. When, about six months later, all escorts were fitted with HF-DF, the Allies gained a huge advantage, as they did also with the coming of short-range radio between warships. Similarly, when there were just a few hard-stretched aircraft operating for only several hours each in the mid-Atlantic, the U-boats benefited enormously. When whole squadrons of very long-range aircraft were operating out of bases in the Shetlands, Northern Ireland, Iceland, Greenland, and Newfoundland (and, after mid-1943, the Azores), and when the Bay of Biscay could be patrolled all through the night by aircraft equipped with centimetric radar, Leigh Lights, depth charges, acoustic torpedoes, even rockets, Doenitz’s submarines knew no rest. A single escort carrier such as HMS
Archer
was a welcome sight to a convoy but could not affect the tactical balance very much. With a dozen escort carriers at sea, by late 1943, the whole situation had changed.

It was small wonder, then, that the Ultra decrypts detected a sharp decline in the morale of the U-boat crews after the May 1943 battles; small wonder that Doenitz’s urgings sounded more desperate. While he possessed more submarines than at any previous time, fewer now pressed home their attacks, and more reported damage and returned to base. Many of their crews were taken into Allied captivity as their stricken boats slowly sank beneath the waves. Captain Herbert Werner, a U-boat commander himself throughout this long war, later wrote a moving memoir; his title,
Iron Coffins,
says it all.
⁴⁰

The overwhelming importance of airpower received further confirmation during the next two phases of this history: the Allies’ aerial offensives in the Bay of Biscay and the failed U-boat attacks on the U.S. convoys to North Africa. These two battlefields were separate geographically, but the struggles unfolded in roughly the same months of 1943 and were in many ways coeval, for if the submarines tiptoeing westward past northern Spain could be destroyed en route, there would be fewer of them surviving to attack the U.S.-Gibraltar convoys or to range farther afield. And if the American escorts on the North African route could batter Doenitz’s wolf packs as savagely as the predominantly British and Canadian fleets had done earlier in the North Atlantic, there would be fewer submarines returning to French bases in any event.

U-boats could cross the Bay of Biscay either on the surface or submerged, and by day or at night, and it was from this that their tactical-technical problem emerged. If they traveled submerged, their speed was much slower, their batteries drained faster (which certainly didn’t help crew morale), and they could still be picked up by the sonar of an enemy warship. On the other hand, if they traveled on the surface, they could reach the wide Atlantic waters faster, though with a much greater possibility of detection by enemy radar, and then they would be at serious risk of aerial as well as surface-vessel attack just when they were most vulnerable. Additionally, by the second half of 1943 Bletchley Park was much more successful at reading German naval codes, and more swiftly, than B-Dienst was in adjusting to the improved Allied ciphers.

These problems were compounded by the fact that Allied aircraft and surface escorts had been transformed by the many technological innovations described above into horrifying submarine-killing machines. It was not just that the Allies were now deploying the new support
groups of powerful sloops and fleet destroyers and the purpose-built escort carriers. It was also the case that the standard, rather plodding workhorses in the Allies’ armory, such as the
Flower
-class corvettes and the medium-range aircraft such as the Wellingtons, the Hudsons, and the Sunderlands, were being steadily improved. In 1940–41 the corvettes were underarmed, underequipped, and horrible sailors against the giant North Atlantic waves (one American observer thought their crews should get submariner’s pay because the vessels seemed to be more than half underwater much of the time). After 1943, those vessels, and the newer types of corvettes and frigates that gradually replaced them and were especially designed for the Atlantic, had much greater horsepower, better detection and destruction equipment, a raised bow, and much more space for the commander’s many functions. On larger vessels, one of the forward guns was now replaced by a Hedgehog; the depth charges were much more powerful and had improved timing devices; and the superstructure sprouted all sorts of antennae, not just the radio mast but the HF-DF and 10-centimeter equipment as well.

The same metamorphosis was true of a Wellington, a sturdy but basic twin-engine bomber originally designed by Barnes Wallis for raids into the western parts of Germany. By 1943 it had, under RAF Coastal Command, become an amazing acoustic machine, spouting aerials along its spine, out of its side, and out of its nose. Its armaments could include forward-firing cannon, rockets, more efficient depth charges, even the new acoustic torpedoes. At night, when its radar brought it close enough to a U-boat on the surface, its massive Leigh Lights would go on, and then the mayhem against the submarines would begin.

Doenitz was nothing if not a fighter, and the German shipyards were producing more U-boats than ever in 1943, which could still reach the Atlantic via roundabout routes through the Greenland-Iceland-Faroes gaps. Recognizing that Allied airpower was now key, Doenitz also persuaded Berlin in autumn 1943 to give his U-boats much more support in the Bay of Biscay than before. In fact, so seriously did the German air attacks upon Coastal Command’s antisubmarine squadrons become at that time that the RAF was compelled in turn to allocate Beaufighter and Mosquito night fighters to protect them. Moreover, a number of U-boats were equipped with far heavier
antiaircraft guns, including four-barrel flak guns, for Doenitz was also encouraging his captains to fight it out on the surface if they could. Finally, the Luftwaffe itself was also being equipped with acoustic torpedoes, as were the newer submarines; in late August German aircraft made their first attacks with glider bombs on two of the escort groups.
⁴¹

Thus, apart from the reduction of attacks in the North Atlantic after June 1943, the fighting over the convoys was not getting any less hectic, nor the wolf packs any less dangerous. Individual actions were as wild as ever. One Sunderland, flying back home across the Bay of Biscay, was attacked by no fewer than eight Junkers Ju 88s, shot down three of them, and got back to land on the pebbles of Chesil Beach on three engines; the German nickname for the Sunderland was “the flying porcupine.” A little later, a furious surface-to-air battle occurred between five U-boats traveling on the surface across the bay together and four Polish-flown Mosquitos. There were British, American, Australian, Polish, Canadian, and Czech squadrons in this phase of the fighting.
⁴²
Some of the planes crashed onto the U-boats, for the shoot-outs between two determined foes distinctly increased that possibility. Occasionally the survivors of any combination of merchantmen, escorts, aircraft, and U-boats might be in their lifeboats and rafts in the same waters and picked up by the same rescue ship. Ramming was common, and among some destroyer captains it seems almost to have been the preferred form of attack—they made sure they crushed the enemy vessel, and they probably also got three weeks of home leave for repairs as well.

But the speed and ferocity of these episodes could not disguise the fact that “the Allied navies and air forces … at last enjoyed adequate strength in the right kinds of ships and aircraft, were trained to high efficiency and equipped with a comprehensive armory for finding and destroying U-boats.”
⁴³
Levels of training had been constantly racheted up, and in any case many of the Allied naval groups and air squadrons had by now considerable experience, which played to their advantage time and again. When a large battle developed in mid-October around convoys ON 206 and ONS 20, the merchantmen and close escorts were supported by no fewer than three highly competent Liberator squadrons (nos. 59, 86, and 120) and by a support group under Gretton,
including, once again,
Duncan, Vidette, Sunflower, Pink,
and
Loosestrife.
One merchantman was lost, and five U-boats went to the bottom.

Operating farther afield from close-escort support, Captain Johnny Walker and his 2nd Escort Group seem to have been given virtually a free hand to pursue his all-consuming passion: sinking U-boats, which they would sometimes stalk for days. By this time Walker had perfected his “creeping attack,” in which only one of his group kept its asdic sender/receiver on and then stayed at a fair distance from a submerged U-boat, whose captain was unaware that the other vessels, with their asdic switched off, were quietly coming right overhead, directed by radio from the control boat. On other occasions, Walker would have his sloops—HMS
Starling, Wild Goose, Cygnet, Wren, Woodpecker,
and
Kite
—advance in line abreast and drop their charges simultaneously, like an artillery barrage on land. Of the two schools of strategic thought about convoy warfare, Walker was definitely
not
of the just-get-the-merchantmen-home-safely persuasion. His operating instructions to the 2nd Escort Group, preserved after the war by the Captain Walker’s Old Boys Association in their home base of Liverpool, reads: “Our object is to kill, and all officers must fully develop the spirit of vicious offensive. No matter how many convoys we may shepherd through in safety, we shall have failed unless we slaughter U boats.”
⁴⁴
Walker was as good as his word. His little group sank no fewer than twenty U-boats from 1943 onward, and he himself gained an astonishing four DSOs before his premature death from exhaustion in 1944.

Walker’s cat-and-mouse tactics were part of a larger Admiralty plan. It will be recalled how, during the convoy battles of early 1943, escort vessels such as
Vidette
and
Pink
had to keep giving up the pursuit of a submarine because of the dire need to return to guard their flocks. In the critical months of March through June 1943, the Admiralty’s Operational Research Department made a detailed statistical analysis of all the encounters between U-boats and Allied escorts over the previous two years.
⁴⁵
It found that if a warship went after a fast-submerging submarine for only a few attacks, the chances of the foe’s getting away were good. If the surface craft could remain in pursuit, perhaps losing but then regaining sonar contact an hour or so later, and especially if it could stay around to drop depth charges in six or more attacks over
more than ninety minutes, then U-boat losses markedly increased. Here, then, was the statistical case for the creation of the support groups, at least if they remained in the general area of the convoys and did not go out hunting for a needle in a haystack. Horton recognized this all along, and it was only the overall shortage of surface warships that had prevented groups such as Walker’s being formed much earlier. But those Operational Research figures did pinpoint Doenitz’s dilemma in a stark way. His boats could stop the flow of Allied supplies to Europe only if they were willing to close with the convoys, but in so doing after July 1943, they were increasingly likely to be detected by aircraft and surface support groups, and hunted down to the end.