Engineers of Victory: The Problem Solvers Who Turned the Tide in the Second World War (11 page)

The Hedgehog was something else, so simple in concept that one wonders why it was not produced during the First World War or much earlier in this war. This weapon was a multiheaded grenade launcher that fired forward of the warship; usually the front 4-inch gun turret was taken out and this dreadful bombard installed in its place. It had several advantages over the depth charge, and Allied escort commanders welcomed its widespread introduction in 1943 with great enthusiasm, even if there were many early teething problems. It really reduced the time it took to fire at the foe. Unlike the proximity-fused depth charge, it exploded on contact—either one hit the submarine or one
didn’t—and, with a fusillade of twenty-four grenades raining down on the desperate U-boat, the chances of a hit were rather good. Moreover, it did not distort sonar readings. After the shot was delivered, its crew could observe with pride the rows of empty spigots, looking very like the bristling spines of a hedgehog.
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The incubator here was a small Admiralty unit called the Department of Miscellaneous Weapons Development (DMWD), fondly known as the “Wheezers and Dodgers.” Its personnel, chiefly scientists, naval officers, and retired military men, was a most eccentric group of characters but also possessed a seriousness of purpose. By the summer of 1940 Britain’s strategic position was quite desperate, its resources low, its armed services battered. Under Churchill’s inspiration the nation planned to fight on, by whatever means possible. It was not surprising that a society brought up on H. G. Wells and Jules Verne novels, the
Boys’ Own Weekly,
and
Amateur Mechanics
should now produce a vast number of citizen-based concoctions intended to help beat Hitler. Most were truly farcical. Still, some of them might, conceivably and with much modification, turn out to be useful after all. Scrutinizing all such weird schemes, and adding its own, was the DMWD’s job. Those efforts fed into Britain’s war machine because a scientific-technological system existed to turn new ideas into reality.
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Among the DMWD’s staff was Lieutenant Colonel Stewart Blacker, by 1942 in his fifties but someone who had been interested in blowing things up since he was a schoolboy in Bedford. Blacker’s earliest success, when still in his early teens, was his attempt to emulate on a modest scale the mortars the Japanese army was using against Russian defenses during the 1904–6 war. Assembling a crude barrel (a circular downpipe) and “borrowing” some black powder, Blacker managed to send his projectile—a croquet ball—into the headmaster’s greenhouse 300 yards away. Thus was his career born. He served in the Royal Artillery during the First World War. By 1940 he had drafted the design for an electrically activated spigot to propel a grenade from a mortar. Further work by the DMWD expanded the weapon into a ring of multiple mortars. There then occurred all sorts of bureaucratic obstacles, plus the creation elsewhere of a rival but much less successful forward-firing mortar. By a stroke of good fortune, Churchill himself witnessed an early test during a visit to an experimental weapons base near his country
house, Chertwell, and breathed life into the scheme.
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Delays still plagued the project, as did the lack of good training for this new and unorthodox weapon; in 1943 a large number of frightened crews had to be hauled back to Tobermory or Loch Fyne for “retraining.” Thus it was only in mid-1943 that “Blacker’s bombard” really came into its own.

By the end of the war, Hedgehogs had destroyed close to fifty enemy U-boats; that was worth a greenhouse or two. Its more sophisticated replacements, the Squid and Limbo weapons systems (whose projectiles could go deeper and actually search for the submarine), added a dozen or more to that total. Unsurprisingly, Squids are still used, in vastly improved form, in today’s navies.

The third improvement, on the Allied side, came in the form of detection of the enemy, especially through radar. At its simplest, detection meant a U-boat spotting an oncoming convoy (or its smoke), or an aircraft or ship catching sight of a distant U-boat. But, once seen, a U-boat could of course submerge out of sight. And a German submarine could, through newer acoustic equipment, hear the welcome sound of the screw propellers of an oncoming convoy, or the more alarming sound of a fast-approaching corvette. To the U-boat’s opponents also, sonar remained the key acoustic instrument for locating another man-made device under the waters. Yet water temperatures could differ vastly from place to place, creating acoustic barriers, and grinding icebergs nearby were a nightmare to detection engineers. Above all, Doenitz’s recognition—arising from his own experiences as a First World War submariner—that U-boats could neutralize Allied sonar simply by attacking on the surface gave the Germans a great advantage. A pack of eight or ten or twenty submarines, creeping on the surface toward a convoy in the moonlight, or a single U-boat, picking off American freighters as they steamed along the floodlit Florida coast, simply dumfounded
all
underwater detection systems. Sonar could work well, but only when the conditions were right.

Doenitz’s altered strategy meant that the U-boats had to be identified
at the surface, and before they launched their assaults. The convoy escorts had to know where the attackers were, how far away they were, how many of them there were, and what their line of attack was. If all that was known, the defense of the merchantmen could be undertaken. The submarines could be countered and, with the right weaponry, driven off, perhaps sunk.

It was not really until 1943 that the Allied navies possessed increasingly effective surface-detecting systems, the first of which was the tactical HF-DF radio-beam identifying mechanism mentioned earlier, but there was also the Admiralty’s invaluable long-range tracking system, which allowed Doenitz’s own messages (if decrypted in time) to be read. This type of direction finder had first been set up early in the war on the east coast of England, to locate German radio senders on the other side of the North Sea. It was not too difficult to reduce the size of the apparatus and move it onto individual warships by mid-1943. “Huff-Duff,” as the Allied sailors fondly called it, was relatively simple and reliable, and it worked well at the ranges that mattered. It could pick up a U-boat’s radio signals close by, and thus bring an escort to the threatened flank for a counterattack, but it could also detect the submarine’s radio traffic as much as 15 miles away, thereby allowing the redirection of the convoy and/or the summoning of additional Allied naval and aerial support by the Admiralty, which was reading the long-range enemy messages. Even now, it seems rather remarkable that Doenitz allowed his U-boat commanders to chatter so much, although he himself was guilty of the same sin. While the actual messages might not be understood by the Allies until Bletchley Park decrypted them, the location of the transmitting submarine near a convoy was easily identified. When an Admiralty plotting team picked up reports from its escort commanders that, say, eight U-boats were forming into a wolf pack, it could send an alert to British forces in the area. Rohwer, reflecting on the outcome of the critical convoy battles of March 1943, identifies HF-DF as “decisive.”
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Centimetric radar was even more of a breakthrough, arguably the greatest. HF-DF might have identified a U-boat’s radio emissions 20 miles from the convoy, but the corvette or plane dispatched in that direction still needed to locate a small target such as a conning tower, perhaps in the dark or in fog. The giant radar towers erected along the
coast of southeast England to alert Fighter Command of Luftwaffe attacks during the Battle of Britain could never be replicated in the mid-Atlantic, simply because the structures were far too large. What was needed was a miniaturized version, but creating one had defied all British and American efforts for basic physical and technical reasons: there seemed to be no device that could hold the power necessary to generate the microwave pulses needed to locate objects much smaller than, say, a squadron of Junkers bombers coming across the English Channel, yet still made small enough to be put on a small escort vessel or in the nose of a long-range aircraft. There had been early air-to-surface-vessel (ASV) sets in Allied aircraft, but by 1942 the German Metox detectors provided the U-boats with early warning of them. Another breakthrough was needed, and by late spring of 1943 that problem had been solved with the steady introduction of 10-centimeter (later 9.1-centimeter) radar into Allied reconnaissance aircraft and even humble
Flower
-class corvettes; equipped with this facility, they could spot a U-boat’s conning tower miles away, day or night. In calm waters, the radar set could even pick up a periscope. From the Allies’ viewpoint, the additional beauty of it was that none of the German systems could detect centimetric radar working against them.
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Where did this centimetric radar come from? In many accounts of the war, it simply “pops up”; Liddell Hart is no worse than many others in noting, “But radar, on the new 10cm wavelength that the U-boats could not intercept, was certainly a very important factor.”
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Hitherto, all scientists’ efforts to create miniaturized radar with sufficient power had failed, and Doenitz’s advisors believed it was impossible, which is why German warships were limited to a primitive gunnery-direction radar, not a proper detection system. The breakthrough came in spring 1940 at Birmingham University, in the labs of Mark Oliphant (himself a student of the great physicist Ernest Rutherford), when the junior scientists John Randall and Harry Boot, working in a modest wooden building, finally put together the cavity magnetron.

This saucer-sized object possessed an amazing capacity to detect small metal objects, such as a U-boat’s conning tower, and it needed a much smaller antenna for such detection. Most important of all, the device’s case did not crack or melt because of the extreme energy exuded. Later in the year important tests took place at the Telecommunications
Research Establishment on the Dorset coast. In midsummer the radar picked up an echo from a man cycling in the distance along the cliff, and in November it tracked the conning tower of a Royal Navy submarine steaming along the shore. Ironically, Oliphant’s team had found their first clue in papers published sixty years earlier by the great German physicist and engineer Adolf Herz, who had set out the original theory for a metal casement sturdy enough to hold a machine sending out very large energy pulses. Randall had studied radio physics in Germany during the 1930s and had read Herz’s articles during that time. Back in Birmingham, he and another young scholar simply picked up the raw parts from a scrap metal dealer and assembled the device.

Almost inevitably, development of this novel gadget ran into a few problems: low budgets, inadequate research facilities, and an understandable concentration of most of Britain’s scientific efforts at finding better ways of detecting German air attacks on the home islands. But in September 1940 (at the height of the Battle of Britain, and well before the United States formally entered the war) the Tizard Mission arrived in the United States to discuss scientific cooperation. This mission brought with it a prototype cavity magnetron, among many other devices, and handed it to the astonished Americans, who quickly recognized that this far surpassed all their own approaches to the miniature-radar problem. Production and test improvements went into full gear, both at Bell Labs and at the newly created Radiation Laboratory (Rad Lab) at the Massachusetts Institute of Technology. Even so, there were all sorts of delays—where could they fit the equipment and operator in a Liberator? Where could they install the antennae?—so it was not until the crisis months of March and April 1943 that squadrons of fully equipped aircraft began to join the Allied forces in the Battle of the Atlantic.

Soon everyone was clamoring for centimetric radar—for the escorts, for the carrier aircraft, for gunnery control on the battleships. The destruction of the German battle cruiser
Scharnhorst
off the North Cape on Boxing Day 1943, when the vessel was first shadowed by the centimetric radar of British cruisers and then crushed by the radar-controlled gunnery of the battleship HMS
Duke of York,
was an apt demonstration of the value of a machine that initially had been put
together in a Birmingham shed. By the close of the war, American industry had produced more than a million cavity magnetrons, and in his
Scientists Against Time
(1946) James Baxter called them “the most valuable cargo ever brought to our shores” and “the single most important item in reverse lease-lend.”
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As a small though nice bonus, the ships using it could pick out life rafts and lifeboats in the darkest night and foggiest day. Many Allied and Axis sailors were to be rescued this way.

To this list of crucial detection instruments that arrived in 1943 might be added the creation of an idiosyncratic former Great War pilot, Humphrey de Verd Leigh, who conceived of patrol aircraft carrying powerful searchlights (named, in his honor, Leigh Lights) that would catch in their stunning glare and paralyze U-boats recharging their batteries at night. Leigh had invented, tested, and paid for this light on his own, solving the technical problems (including flying with the prototypes), but then had a hard time getting Air Ministry support, which delayed at least by a year its general use in Allied aircraft. No doubt U-boat commanders crossing the Bay of Biscay at night wished it had been delayed forever.
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Although all were developed separately, when they were brought together, the Leigh Light, the increasingly improved variants of HF-DF, the cavity magnetron, and the airborne homing torpedo became interacting pieces in a single platform such as a Sunderland bomber. This much diminished a U-boat’s chances of escaping detection, attack, and destruction.

By comparison, the contest between the code breakers at Bletchley Park and their archrivals in the B-Dienst seems a less decisive factor in the Battle of the Atlantic once a detailed analysis of the key convoy battles of 1943 has been undertaken. It was certainly far less important than most of the popular literature about the code breakers suggests. From the first revelations of around 1970 to the present day, the reading public has been fascinated by the idea that before the war the German armed forces possessed a super-clever mechanical gadget that could turn all messages and reports into an undecipherable mishmash of symbols that could be understood only if the recipient had a similar machine to decrypt these documents. They were even more fascinated by learning that, at a top-secret location, the British, aided first by the Poles and later by an American contingent, had machines that could
read those messages—until the Germans made transmission more difficult, frustrating the Bletchley code breakers for months until they cracked the newer system. Equally exciting was that Doenitz’s own B-Dienst was doing the same thing—reading Admiralty codes. And in the Pacific the U.S. code-breaking services were reading Japanese military and diplomatic messages through their Magic and Purple systems. Here, surely, was a new way of understanding the outcome of the war, an ultimate explanation of why the Allies won.