Black May (12 page)

The technology was co-invented in 1934–35 by the British (Scottishborn) engineer Robert Watson Watt, superintendent of the Radio Department of the National Physical Laboratory near the Berkshire town of Slough, and by American engineers, notably Robert Morris Page, Albert Taylor, and Leo Young, at the Naval Research Laboratory at Anacostia in Washington, D.C. Thanks to the original research of Watson Watt, who is customarily called the “father” of radar, British engineers were able to erect the famous Chain Home radar network that, by providing range, course, and altitude of incoming Luftwaffe bombers and fighters, helped the RAF to win the Battle of Britain in 1940.

Quickly miniaturized, RDF sets were installed in RN escort vessels beginning in fall 1940. This first equipment, Type 286 (1.5 meter wavelength), could obtain echoes on a trimmed-down U-boat at no more
than 1,000 meters; hence, except in moonless nights or in fog, it was frequently outperformed by a human lookout. By March 1941 about ninety escorts were so equipped. In the same month and year Type 271 (10-centimeter, or S-band) radar was fitted to an escort, the corvette H.M.S.
Orchis.
When 271 entered general service with the escort fleet in 1941–42, U-boat detection range jumped to 3,000–5,000 meters. By May 1942, 271 was mounted on 236 RN ships of all categories.

The 271 was made possible by a remarkable device called the resonant multi-cavity magnetron valve. The invention of two British physicists at the University of Birmingham, John Randall and Henry Boot, the cavity magnetron’s central feature was a cathode and anode structure built into a block of copper through which either six or eight symmetrical holes were bored. The high-frequency radio oscillations produced by the device enabled a radar apparatus to operate on a wavelength of 9.7 centimeters—rounded out in popular usage to “10-centimeter,” or “centimetric” radar.
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This represented an extraordinary advance in power, range, and accuracy over the previous “metric” radar, and constituted, in the words of Britain’s most accomplished air and naval operations research scientist, physicist Patrick M. S. Blackett, “one of the most decisive technical developments made during the war.”
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Its narrow horizontal beam width enabled a single escort to find, fix, and hold a nearby U-boat on the surface at night and in fog. And from its first operational use until the fall of 1943, its beam was not detectable by any German search receiver then at sea. A U-boat Commander proceeding on the surface at night near a convoy escort had no way of knowing that he was being “painted.” But in the plot, or operations room, of the nearby escort, that U-boat was exposed starkly on the 271's plan position indicator (PPI), where a sweeping radial line from the center of the circular CRT screen rotated in synchronization with an outside antenna and, each time it passed the U-boat’s position, displayed it as a bright phosphorus-lit spot.

In September 1940, a seven-member British Technical and Scientific Mission to the United States, headed by physicist Henry Tizard, arrived in Washington, D.C., with a black solicitor’s box containing, among other scientific objects and blueprints, a hand-sized eight-cavity
magnetron. The gift was not entirely magnanimous: the British knew that to win their war they would need American technological assistance and industrial capacity. Members of Tizard’s mission, which was conducted at the height of the Battle of Britain, were mindful, too, that their homeland might soon be invaded; if the war was lost in the Old World, this means for continuing the fight would be in the hands of the New.

Grateful U.S. radar specialists acknowledged that the gift put them two years ahead of the curve, and James Phinney Baxter III, official historian of the U.S. Office of Scientific Research and Development, was moved to write in 1947, “When the members of the Tizard Mission brought [a cavity magnetron] to America in 1940, they carried the most valuable cargo ever brought to our shores.”
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The encomium should not be accepted uncritically to mean that centimetric radar alone, or even principally, won the war at sea. By itself it was not a war-winner, though one could certainly say it was a
battle
winner, as in the final stage of the surface battle for Convoy ONS.5 (chapter 7), where centimetric radar was the triumphant technology. In the regular structure of surface engagements between escort vessels and U-boats, centimetric radar fell into place as one of five technological innovations that, taken together, swept the field. The first four were, in the order in which they were employed: (1) HF/DF; (2) radar; (3) hydrophone effect (using asdic to listen for underwater noise such as cavitation from a U-boat’s propellers); and (4) asdic echo contact. (Close in, one must not discount the Mark I eyeball.) The fifth innovation was TBS (Talk Between Ships), an American-developed very high frequency (VHF) voice radio-telephone (R/T) system, introduced in early 1941 and universally fitted on escorts a year later. At low power and short range it was immune to DFing. TBS enabled an escort commander to give instantaneous direction to the movement of his ships and to converse with overhead air cover. It also enabled the individual surface escorts to coordinate attack maneuvers between and among themselves. It is clear that by the date of the May 1943 battles, an Atlantic escort was an electronics platform of daunting authority.

RAF Coastal Command began the war with a fleet of Avro Ansons (301), Lockheed Hudsons (53), Vickers Vildebeests (30), Short Sunderlands (27), Saro Londons (17), and Supermarine Stranraers (9). The most numerous aircraft, the Anson “Annies,” which entered RAF service in 1936, were obsolescent, and by the close of 1941 had been replaced by Wellingtons, Halifaxes, Whitneys, and other advanced designs; so, too, the Vildebeests, Londons, and Stranraers were struck off the inventory. The Hudsons, an American passenger plane refitted as a bomber, continued to be purchased and used in large numbers.

But the principal survivors among the original list, which in fact soldiered on to the end of the war, were the Sunderland flying boats. Admirably equipped for long-range anti-submarine patrols, the “Queens,” as air crews called them (U-boat crews, noting their languorous flight maneuvers, called them
mtide Bienen,
“tired bees”), would score the second-highest U-boat tally of the war. Third in ranking would be the Vickers Wellington, a two-engine bomber never designed for maritime operations, but greatly effective in the Bay of Biscay (see chapter 8). Two American designs that came on the scene in 1941 and performed well were the Boeing B-17 Flying Fortress, a four-engine heavy bomber, and the Consolidated PBY-5 and PBY-5A (amphibian) Catalina twin-engine flying boat.

The overall favorite aircraft in Coastal Command and the most successful sighter and destroyer of U-boats was the four-engine Consolidated B—24 Liberator heavy bomber. Though somewhat harder to handle, more demanding in maintenance time, and certainly more drafty than the Fortress, the Liberator was esteemed for its range. In a V.L.R. (for Very Long Range) modification, where weight reduction was achieved by removing self-sealing liners (if present) to the fuel tanks, most of the protective armor plating, the turbo-superchargers, and the belly gun turret, the Liberator had a low-altitude operational range of 2,300 nautical miles at an economical 150 knots, while carrying, on takeoff, 2,000 gallons of high-octane fuel and eight 250-pound depth charges (gravity bombs with hydrostatic fuses). This was the aircraft that would give overhead coverage to threatened convoys in distant midocean lanes, force shadowing U-boats to submerge (which until
May 1943 they uniformly did on sighting a reconnaissance bomber), and thus retard their speed, maneuverability and visibility, hence, their potential for organizing packs. This was the aircraft that, operating from both shores of the Atlantic, would eventually plug the Air Gap between Iceland and Newfoundland in May 1943—assisted by newly introduced carrier-borne aircraft.

No. 120 Squadron received the first Mark I Liberators in June 1941 and in September began flying nine of them southwestward from bases in Northern Ireland and Iceland to their Prudent Limit of Endurance (PLE), governed by fuel remaining. But the numbers of these aircraft in Coastal remained depressingly few, as American Admiral Ernest J. King, Commander in Chief, United States Navy (after 30 December 1941), hoarded most Navy-assigned Liberators (designated PB4Y-1) for the Pacific theater, while almost all of the RAF-assigned Liberators that made it to the U.K. were claimed by Bomber Command. By September 1942 Coastal still had only one squadron (No. 120) containing V.L.R. Mark Is, six in number. The V.L.R
.s
were “being allowed to die out,” Coastal complained to the Under-Secretary for Air. The squadron list also included two Mark IIs (range 1,800 miles) and three Mark Ills (1,680 miles). Other squadrons had PBY-5 Catalinas (1,840 miles) and PBY-5AS (1,600 miles), but the V.L.R. was the most desperately needed long-distance performer. (There were none in Newfoundland, Canada, Gibraltar, or West Africa.) And Coastal’s Atlantic operations were being denuded of other essential resources, including, between October 1941 and January 1942, 166 air crews and whole squadrons of Catalinas shipped to overseas bases.

Penetration by GC&CS of the German naval cipher and the development of a fairly accurate plot in the OIC Tracking Room made it possible, on 9 May 1941, for the Admiralty to draw a distinction between threatened and nonthreatened convoys. Coastal thereafter concentrated its forces on threatened convoys, thus making more efficient use of its air assets, but without V.L.R. aircraft, sorties directed to threatened convoys outside a radius of 450 miles from air bases could not be sustained beyond a short period of time, and Coastal began to worry about “the lavish expenditure of engine hours in order to get, at most, two or three hours with the [threatened] convoy.”

Even on as late a date as February 1943, when Air Marshal Sir John Slessor took over as Air Officer Commanding-in-Chief (AOC-in-C), Coastal Command, No. 120 still remained the lone operating V.L.R. squadron. Based at Aldergrove in Northern Ireland with a detachment at Reykjavik, Iceland, it then counted among its assets five Mark Is and twelve Mark IIIAs modified to V.L.R. requirements. A new squadron with modified Mark IIIAs was forming at Thorney Island, near the Isle of Wight on the southern coast of England, but it was not yet operational; neither was No. 502 at nearby Holmsley South, which was awaiting V.L.R.-modified Halifax lIs. And still, by Admiral King’s decision, there were no Liberators in Newfoundland. When Convoys SC.122/HX.229 were pummeled in the following month, President Franklin D. Roosevelt pointedly asked King where all the Navy Liberators had been.

That more of the Liberators then in the U.K. had not been allotted to ASW work was owed to the fixation of RAF Air Staff (abetted by Churchill) on night bombing of Germany. Contention between Coastal and Bomber Commands over the question of which targets, U-boats or factories, would more effectively create a matériel advantage for the Allies’ cross-Channel invasion of the Continent simmered all through the first six months of 1943. The doctrinal dispute, which, particularly in March of that year, involved heavy-handed wrestling over bomber allotments, extended to the question, Was the U-boat force better destroyed at sea (Coastal) or at its construction and assembly yards (Bomber)?

Historians who incline to the Coastal position in that debate can only wonder how much earlier and more thoroughly the U-boat threat might have been brought to an end had the majority of V.L.R. Liberators not been concentrated on land warfare, where postwar analysis showed that overall German war production had not been substantially reduced by Allied bombing and that “de-housed” civilians—a Bomber Command term—had not faltered in morale. In a recent book, Clay Blair writes: “A number of studies would show that a Coastal Command ASW force of merely a hundred B-24S could well have decisively crushed the U-boat peril in the summer of 1941, sparing the Allies the terrible shipping losses in the years ahead.” That might be pitching it a
little high, since the essential improvements in attack procedures described in the following chapter were not all in place during 1941, but the point is well taken.

A smaller number than a hundred V.L.R. bombers is proposed as sufficient in 1942–1943, when Coastal attacks were far more lethal than before, by a historian of the maritime air war, Alfred Price. He holds that three squadrons, comprising about forty aircraft, “would have gone—and later did go—a considerable way towards nullifying the threat to convoys in mid-Atlantic.” And the transfer of that number to Coastal from Bomber Command would not have appreciably weakened the bombing offensive over Germany. After all, Price points out, many times Bomber Command was losing that number of bombers in a single night.
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By the end of 1942 none of Coastal’s aircraft was equipped with centimetric radar. Not until February 1943, after resolution of numerous technical problems and intense competition between Coastal and Bomber Command for the equipment, was the Telecommunications Research Establishment (T.R.E.), of the Ministry of Aircraft Production, at Malvern in Hereford and Worcester (after May 1942), able to fit ASV (Air to Surface Vessel) Mark III 10-centimeter radar to Coastal Liberators, Wellingtons, Sunderlands, and other reconnaissance bombers. In the meantime, since 1940, Coastal aircraft operated with metric (1.5 meter) ASV Mark II equipment, which was unsatisfactory for several reasons: limited range, approximately 10 miles maximum; unclear returns because of sea clutter; a hard-to-read light-bar graph display; poor construction resulting in numerous failures and difficult servicing; chronic shortage of parts; and poor training of operators.
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When in December 1941 Coastal Command Headquarters at Northwood in Middlesex reflected on the maritime air war to date, it could count fewer than a handful of kills and one capture, most of them shared with surface vessels. A force that was projected from the outset to have an offensive, not defensive, purpose, as yet Coastal was not meeting its mark. At fault was not a lack of commitment. Coastal had responsibilities other than the anti-submarine war, for example, protection
of the United Kingdom’s coastal waters and destruction of enemy shipping, but by 1941 its main effort was clearly directed at the U-boats. Kills had not materialized in the expected number because of aircraft shortages, particularly in the long-range category, inadequate search tactics, poorly executed attack procedures, and the above-mentioned radar deficiencies, but since May 1941 Coastal air was performing at least one indisputable service by concentrating “scarecrow” patrols over threatened convoys, while leaving unthreatened convoys on their own.