Black May (15 page)

Blackett undertook additional studies of depth charge attacks (later continued by Dr. E. C. Baughan), which, like the 25-foot D/C setting, led to considerable improvement in lethality. Although Coastal personnel engaged in much discussion about bomb weight, some proposing D/Cs of 35, 100, or 600 pounds, Blackett was convinced that the current 250-pound weapon, with its 19–20 foot killing range, was perfectly serviceable if it was used correctly. He investigated its use under two categories: (1) aiming accuracy and (2) stick spacing. (A
stick
was a group of four to eight individual D/Cs dropped either all together as a salvo or, more often, in a series. In a series drop, an electromechanical intervalometer was used to establish the distance between the D/Cs, that is, “stick spacing.” The overall length of the D/C string was the “stick length.”)

For accuracy studies Blackett had a rear-facing mirror camera fitted to bombers and examined what the attack photographs showed, which was that pilots were placing the center of the stick length at a point 60 yards ahead of a surfaced U-boat’s conning tower. When asked why, pilots told him that it was “aim-off” to allow for the forward travel of the boat during the interval when the D/Cs were falling. This was in the manual; it was how they had been trained. But the photographs showed that the aim-off was not working. Blackett advised Joubert to have the pilots aim bang-on at the conning tower, even though it seemed to violate common sense. When they started doing so, kills increased by 50 percent.

The optimum stick spacing was a more complex problem, the resolution of which was not reached until after Blackett’s departure from Coastal in January 1942. Current practice of pilots was to set for 36 feet between charges, but mathematical analysis suggested that this was too short. The O.R.S. recommendation that the spacing be increased to 100 feet was accepted by the Coastal staff in March 1943, after which straddles of a U-boat with 100-foot spacing were increasingly lethal.

O.R.S. attacked many other problems, some as mundane as what
came to be called Planned Flying and Maintenance, pursued by Dr. C. E. Gordon, whose aim was to make maximum possible use of crewmen and aircraft. Gordon found that in a typical squadron of nineteen aircraft only 6 percent of the time (in hours) was spent in the air; 23 percent on the ground even though crews were available and aircraft were operational; 30 percent in repair or maintenance; and 41 percent waiting on spare parts or manpower. If efficient use could be made of Coastal’s already existing resources, the force at sea could be greatly enlarged. Gordon’s “efficiency study,” as one would call it today, led to a near doubling of flying hours—a squadron of nineteen increasing from 1,300 to 4,000 hours—and proportionately greater peril to U-boats. The O.R.S. system was eventually adopted throughout the RAF and the Naval Air Division.

Other O.R.S. members, particularly the mathematicians, worked on more arcane problems, such as aircraft operational sweep rate and width; sighting ranges of various aircraft and of the various sighting positions within an aircraft; optimum altitudes for visual and radar searches; eye rest requirements for crew; probability-of-kill-given-sighting; open water navigation technique; the average number of convoys sighted by a U-boat during its lifetime (seven and a half), the average life expectancy of a U-boat (14 patrols), and development of what today would be called a “macro-model” of U-boat circulation in the North Atlantic.
²⁹
In January 1942, as earlier noted, Blackett left Coastal. His place as Officer in Charge was taken by Professor Williams. The section’s work continued as before, with what might be called even closer association of uniformed Command and civilian scientist after 6 February 1943, when Air Marshal Sir John Slessor succeeded Joubert as AOC-in-C.

Waddington testified that “At least in the sphere of my experience, I have rarely met such critical generosity of mind as was shown to us civilian ‘intruders.'” At no time, it appears, was there the slightest concern on the part of Joubert or Slessor that the “suck it and see” scientists sought an unwarranted prominence for themselves or ever considered themselves as anything other than members of a team.
³⁰

In citing the contributions to Coastal of non-RAF personnel, special
mention should be made of the senior Naval Liaison Officer, Commander, later Captain, D. V. Peyton Ward, R.N., who was the very embodiment of the close and fruitful relationship that existed between Coastal and the Admiralty. An invalided-out submariner, “P.W.,” as he was affectionately known at Northwood, volunteered for tasks not normally required of his position, and after Joubert’s arrival he took it upon himself to interview all returning aircrews who had sighted and/or sunk a U-boat. By writing up and analyzing each such incident, he greatly enlarged the attack data available to O.R.S. A navy-blue in the midst of RAF slate-blue, he represented Coastal on the important interservice U-Boat Assessment Committee, which judged the success of surface and air attacks. After the war, he wrote the official four-volume history of air operations in the maritime war.
³¹
All the while O.R.S. and P.W. were bending their minds, the aircrews practiced their own difficult art of air search, hundreds of miles out over the Atlantic’s gray flannel, noisily patrolling 1,000 to 5,000 feet off the deck, in every kind of weather, dirty and cold, rarely if ever in their entire flight careers sighting a single U-boat to reward them for their protracted and boring hours. Said one crewman:

And many crews would be shot down, in distant positions where no assistance was near or possible. And many other crews were lost to the sea not through enemy action, but through engine failure, adverse weather, navigational error, and fuel depletion.

The Bay of Biscay is a roughly triangular body of water bordering the Atlantic that is formed on the north by the Brittany peninsula of France, where it does an arabesque toward Land’s End on England’s Cornwall coast, and on the south by the northern provinces of Spain.
About 86,000 square miles (223,000 square kilometers) in size, and 15,525 feet (4,735 meters) deep at its center, it was the body of water traversed by U-boats operating out of bases at the western French ports of Brest, Lorient, St.-Nazaire, La Pallice, and Bordeaux. Normally, outbound and inbound boats transited through a zone, or “choke point,” about 300 miles north to south and 200 miles east to west. Here, more than at any other sea position, U-boats could be found in high concentration: traffic ranged from forty-five boats per month in June 1942 to a figure that, in early 1943, passed 100 (expected to increase to 150 by spring). The Strait of Gibraltar was another choke point, but far fewer boats attempted its passage; and the northern route from Germany around the north of Scotland was another transit area, but one that was used almost exclusively by new boats coming into Atlantic service. If one wanted to find a large number of U-boats bunched up in any one place, it would be in the transit zone of the Bay of Biscay.
³³
In March 1943, the Admiralty said of the enemy:

Whether U-boats were bound to and from the midocean transatlantic convoy lanes, where the most intensive pack battles were fought, or to and from what the British called the Outer Seas—Freetown, Cape Town, the Indian Ocean, the Atlantic Narrows, Brazil, the Caribbean, and the North American seaboard—the swept channels of the Biscay minefields were the narrow funnel through which every boat had to pass. To an adversary with marksman instincts, the Bay presented an irresistible bull’s-eye.

From the date he assumed command at Northwood in 1941, Air Chief Marshal Joubert cast a malevolent glare in that direction. Like many at Coastal before him, he could not understand why Bomber Command with its heavy bombardment squadrons had not destroyed the steel and concrete U-boat bunkers while they were still under construction and vulnerable. As a matter of fact, Bomber Command did
attempt to disrupt construction, making twenty nighttime raids on the Lorient base in 1940, sixteen in 1941, and twelve in early 1942. The U.S. Eighth Air Force made ten daylight raids on St.-Nazaire between November 1942 and June 1943. Other raids were mounted against Brest. All such raids were ineffectual, owing to poor bombing accuracy and to intense anti-aircraft fire that caused heavy bomber losses. The only result on the ground was the flattening of the towns where the bases were situated. Of Lorient and St.-Nazaire, Admiral Donitz said that not a cat or a dog survived. Left with the problem of nearly completed bomb shelters, Joubert decided that since Coastal Command was envisioned to be an offensive instrument and the hunter role suited his nature, he would direct as much of its power as he could spare from convoy escort to that of offensive patrol against U-boats transiting the Bay. In making that decision, he entered a debate that would never be completely resolved, either in Coastal or the Admiralty: whether ‘tis nobler to
defend
convoys and so win the Atlantic by seeing merchantmen to safe and timely arrivals at their destinations, or to take up arms against a sea of U-boats, and by
hunting
, kill them?

What came to be called the First Bay Offensive, launched by Joubert in the summer of 1941, was a daytime operation flown by Sunderlands, Wellingtons, Whitleys, Hudsons, and Catalinas, all of them equipped with 1.5-meter wavelength ASV Mark II radar. It yielded very disappointing results. O.R.S. analysts discovered that 60 percent of the U-boats sighted the approaching aircraft before being spotted themselves, and thus were able to dive out of harm’s way. As the campaign wore on into autumn, it became clear that transiting U-boat commanders, alerted to the increased presence of aircraft in the Bay, were charging their batteries on the surface at night and traveling as much as possible submerged during the day. Sightings of boats decreased accordingly, and the record shows that the year ended without a single U-boat kill by aircraft in the Bay.
³⁵

What was needed, argued Professor Blackett of O.R.S., who chaired a specially organized Night Attack Sub-Committee under the ASW Committee on Aircraft Attacks in the Admiralty, was an effective means of delivering attacks during darkness when the U-boats
were on the surface charging. And that meant an illuminant that could display to the pilot’s eye targets detected first by radar. In early 1942 combat experiments were run using 4-inch flares towed by radar-equipped Whitleys, but these proved unsuccessful. Another, more promising illuminant was waiting in the wings.

When in September 1940 the then AOC-in-C Air Chief Marshal Bowhill sent around a memorandum asking officers and airmen to submit ideas for improvement of ASW operations, he received back a detailed proposal for an airborne searchlight for use in night attacks on surfaced U-boats. It came from a nontechnical source, a World War I pilot who had flown ASW patrols over the Mediterranean in that conflict, named Squadron Leader Humphrey de Verde “Sammy” Leigh, now serving as Assistant Personnel Officer in headquarters administration. Leigh proposed that the so-called DWI Wellingtons, which had earlier, but no longer, been used to explode magnetic mines from the air by generating a powerful electrical charge, be refitted with a belly-installed retractable carbon arc lamp. The DWIs recommended themselves for this use because they were already equipped with auxiliary engines and either 35-or 90-kilowatt generators.

Bowhill was so impressed by the idea that he relieved Leigh of his desk duties and set him to work full-time on the project. There were numerous obstacles to overcome, starting with the technicians at RAE, Farnborough, who argued the case for towed flares as preferable to the searchlight scheme. The nontechnician Leigh pressed on regardless, and ingeniously solved every problem that he encountered, among them ventilation of the carbon arc fumes, steering control of the lamp’s beam in azimuth and elevation, prevention of back glare, or “dazzle,” and reduction of weight. In March 1941 the Vickers plant at Brook-lands completed a prototype installation employing a naval 24-inch (61 cm) narrow-beam searchlight, giving a maximum 50 million candles without a spreading lens, powered by seven 12-volt 40-ampere-hour type D accumulators (storage batteries); and on the night of 4 May, with Leigh himself operating the light controls in the nose, the first Leigh Light Wellington repeatedly detected, illuminated, and “attacked” the British submarine
H
—31 off Northern Ireland. Bowhill
was no less gratified at this success than Leigh, but only one month later, when Bowhill was relieved by Joubert, the whole project was canceled and Leigh found himself reassigned to a desk.

It happened that Joubert had been associated with the development of a competing airborne light system called the Helmore Light, after an RAF Group Captain, which had been designed for illuminating enemy bombers at night, and the new AOC-in-C thought it should be used against U-boats as well. But the Helmore Light was quickly shown to be unsuitable for Coastal work: its massive array of accumulators occupied the entire bomb bay; the light could not be steered, or aimed, except by moving the entire aircraft; and the brightness of the light, which was mounted in the nose, dazzled both the operator and the pilot. “After some two months I found, as I do not mind admitting,” Joubert wrote later, “that I had made a mistake.”
³⁶
Leigh cleaned out his desk a second time and returned to the hangar.

Months of redesign, flight testing, crew training, and what Peyton Ward called “difficult to explain” administrative delays followed, until finally, at the beginning of June 1942, a “penny packet” of five Leigh Light (L/L) Wellingtons of No. 172 Squadron entered operational service in the Bay. The first L/L-assisted attack was made on 4 June against the Italian submarine
Luigi Torelli
(Tenente di Vascello [Lt.-Cmdr.] Augusto Migliorini), resulting in severe damage.
³⁷
The attack was made by Squadron Leader Jeaff Greswell, flying Wellington “F” of 172 Squadron. During June and July the Wellingtons, showing what the surprised and helpless Germans came to call
das verdammte Licht—
“that damn light”—made altogether eleven sightings and six attacks, resulting in one kill—the Type IXC U-502 (Kptlt. Jürgen von Rosenstiel) en route home from the Caribbean, sunk by Wellington VIII “H” flown by Pilot Officer Wiley Howell, an American serving with the RAF—and two boats damaged.