Seizing the Enigma (45 page)

F-21’s Submarine Tracking Room, itself a confidential operation, was the only area through which the Secret Room could be entered. The Secret Room, F-211, was kept locked, and only the three men who worked in it, together with Knowles and a relief officer, had keys; no one else was admitted except a few higher-ups with special permission. In charge was a New York lawyer and naval reservist, Lieutenant John E. Parsons. As the intercepts came to the Secret Room, Parsons and his assistants entered the information on a daily location list of U-boats. From here it was transferred to one of three large wall maps—the North Atlantic map was 12 feet wide—on which the U-boats were represented by pins. Each one carried the bigram assigned by the Admiralty to that submarine, the skipper’s name, the date of the position, and a colored tab to show whether it was a refueler, minelayer, cargo carrier, or combat sub. Other wall charts showed U-boats at the five Biscay bases, areas in which U-boats used particular frequencies (helpful in locating U-boats to which Dönitz sent messages), places where submarines had been sunk in the past month, and the results of OP-20-GI-2(A)’s special studies, such as one on areas that Dönitz considered especially dangerous because of aircraft. In addition, the Secret Room contained a card file of U-boats; logs of attacks on ships and on U-boats; a list of skippers; files of U-boat arrivals and departures, fuel, destroyed U-boats, and flotillas; and assessments of attacks on submarines. All of these depended on information that had been abstracted from the intercepts.

Intelligence moved out of the Secret Room in a variety of ways. Individuals, including King, viewed the charts and had the briefing officer in the room answer their questions. Every ten to fourteen days one of Parsons’s assistants prepared a summary of trends in U-boat operations as well as of new tactics and equipment; this went to the officers who had access to F-211. Messages were sent to the Admiralty about U-boat identifications, which ones were involved in attacks,
and similar matters. And the Secret Room staff gave the cryptanalysts information, using a special telephone for short items and notes for more complicated ones.

As head of Atlantic combat intelligence, Knowles was probably the chief consumer. His unit combined Parsons’s
ULTRA
intelligence with intelligence from direction-finding, prisoners of war, action reports from Allied merchantmen and warships, reconnoitering airplanes, and other sources to figure out the U-boats’ daily estimated positions. The Submarine Tracking Room had an officer and three enlisted men on watch at all times; the
WAVES
eventually replaced all the men except two officers not qualified physically for sea duty. (Captain Henri H. Smith-Hutton, who headed Combat Intelligence in 1943 and 1944, maintained that the plotting room ran better with the
WAVES
than it had earlier because the displaced men “were not as smart as these carefully selected
WAVES
.”) Probably Knowles himself drafted or at least approved the daily U-boat situation estimate, with its forecast of where the submarines were going, that was transmitted to task forces at sea under the signature of the commander in chief, U.S. Fleet.

Knowles’s detailed information went across the hall to the Tenth Fleet’s Convoy and Routing Section, F o. This body, the American version of the Admiralty’s Trade Division’s Movements Section, directed shipping in the U-boat-infested waters.

On a 40-foot-wide chart of the North Atlantic covering one wall of this room, U-boat positions were continually updated with pins. The section never knew that the submarine locations were furnished by codebreaking, though some suspected it; the cover story was that direction-finding provided this information. As the officers saw that “their” ships were about to encounter U-boats, they ordered diversions to detour them away from the submarine danger.

Among the convoys that twisted and turned in response to the section’s orders was SC 127.

F
OR HOURS ON
F
RIDAY
, A
PRIL 16, 1943, A FEW DOZEN SHIPS
furrowed the waters of the 10-mile channel to the sea from the bustling port of Halifax, Nova Scotia. They steamed between the red sand cliffs to starboard and the white granite hills to port that guarded the narrow entrance. Out on the ocean they arranged themselves into a convoy’s customary broad-fronted formation. Convoy SC 127 had been born.

Its fifty-four ships, plus three that joined later from St. John’s, were taking to Britain material both for the British war economy and for the eventual invasion of western Europe. The
Fort Howe
and the
Picotee
and the
Belgian Sailor
all carried tanks and grain. The
Keilhaven
and the
Mimosa
carried steel and lumber. No fewer than nine ships had explosives in their holds. Others were bringing over fuel oil, lubricating oil, sugar, and phosphates. The commodore’s ship, the
Empire Franklin
, carried general cargo. Most were headed for Loch Ewe in northern Scotland; others for Glasgow, Belfast, Liverpool, Manchester, London.

The Atlantic into which they were heading was the theater of a battle in which the Germans seemed to be approaching victory. In 1942, the Germans had sunk more tonnage than the Allies had built. The daily average of U-boats in the Atlantic and Arctic rose from 92 in January 1943 to 111 in April. The number of Allied ships sunk almost doubled month by month: 29 in January, 50 in February,
95 in March. Indeed, March saw the greatest convoy battle of the war, when 45 submarines swarmed around convoys SC 122 and HX 229, sending dozens of ships to the bottom.

And this was happening at a time when, though it had become clear that Britain would not starve and her factories would not close down, severe shortages persisted. Stocks of food and goods had not yet recovered from having been drawn down during the previous year. Imports to Britain had in January reached their lowest level of the war. Beef and veal imports had begun their 1943 slide to 310,000 tons, about half the yearly prewar average. Rationing continued. Each individual was entitled to two ounces of tea per week and four ounces of bacon and ham. The cheese ration had been halved in February from the generous eight ounces of 1942.

The Ministry of Food sought to reduce the amount of wheat brought in, on which Britain was especially dependent: in 1939 she had produced 1,668,000 tons but had imported 8,519,000, The ministry considered raising the rate of extraction of flour from wheat from the customary average of 70 to 75 percent to 90 or 95 percent and diluting the flour with barley and oats, even though this would produce a darker, less palatable, and less digestible bread. But the barley could be obtained only by reducing beer production and closing the pubs two days a week. The committee in charge unanimously recoiled from this. It and the brewers finally agreed, however, that oats and dried potato bits would replace 10 percent of the barley used in brewing. The plan was put into effect, and 280,000 fewer tons of wheat had to be imported. Such were the contortions the British government went through to save shipping space.

At the same time, the euphoria of the Casablanca conference, at which Roosevelt and Churchill planned their next offensive and declared the war against the U-boats their priority, had all but worn off among the Allies’ military chiefs. They had come to see that the shipping situation was far worse than their earlier vague, optimistic impressions. The War Office miscalculated the number of vehicles
and therefore the amount of shipping space per man needed for the North African invasion. Also the number of troops for that operation constantly increased, and, owing to the unexpected strength of the enemy opposition, the date when the buildup would be complete continually receded. Instead of the thirty ships a month that maintenance of the North African offensive had been thought to require, ninety-two sailed in February, seventy-five in March, and thirty-eight in April. Meanwhile, Turkey demanded 150,000 tons of grain that had been promised to keep her from raiding her traditional enemy, Russia. So tight was shipping that, far from being able to mount the operations against Japan that the Allies had grandly planned at Casablanca, Britain’s Ministry of War Transport was haggling over single ships on the routes to India and the Middle East. Famine loomed in Ceylon, where laborers were leaving the rubber plantations in search of food, and in East Africa, where Britain feared that the shortage of food would cause a breakdown in work at the main repair base of the Eastern Fleet in Mombasa. Ultimately, one and a half million people died of starvation or its diseases in British-ruled India.

All of this exerted extreme pressure on shipping, the shortage of which, the chief of the Imperial General Staff said, put “a stranglehold on all offensive operations.” And though details were probably not known to the codebreakers of Hut 8 or OP-20-G, they certainly felt the great and relentless need to save as many Allied ships as possible.

Convoy SC 127—codenamed for that series of convoys’ original starting place, Sydney, Cape Breton Island, Nova Scotia—was a slow convoy, one that could not maintain a speed of 10 knots; a fast convoy was one that could maintain that speed. But since no convoy could steam faster than its slowest ship, slow convoys averaged 7 knots, fast, 9. SC 127’s planned speed was 7.5 knots.

Because the British Isles are several hundred miles farther north than Nova Scotia, each convoy had to head north somewhere along its course. SC 127’s course, established nine days before sailing, called
for it to start by sailing to Point F, at 46° 30′ north latitude, 46° 02′ west longitude, slightly north and well east of Halifax. From there, it would swing more to the north for a long leg to Point G, several hundred miles southeast of the tip of Greenland. Thence it would turn sharply eastward and then due east for the long run over the north of Ireland. If intelligence showed submarines lying along this route, it would be changed. And in fact, two days after it laid out the course, the Admiralty added some lettered points closer to Halifax, taking the convoy a bit south before it turned north.

The course changes were devised by Commander Richard Hall’s Trade Movements Section to avoid U-boat packs. The section based its plans on the reports of Winn’s Submarine Tracking Room, which depended heavily on the solutions put out by Hut 8 and OP-20-G. On April 16, when the convoy put to sea, the codebreakers were running three days behind in their solutions. But since this was the best available information, the two Submarine Tracking Rooms continued to issue their reports on the positions of enemy U-boats. The U.S. report for April 16 situated twenty to twenty-five U-boats in a rectangle bounded by 47° and 53° north and 44° to 37° west. The path of SC 127 that had been planned on April 7 ran right through this area. Hall would have to attend to that.

In the open sea SC 127 had formed itself into thirteen columns, of four or five ships, a pattern that reduced the number of shots a U-boat could get at the ships, compared to an arrangement with fewer but longer columns. The convoy’s size, fifty-four ships, reflected a lesson learned from operational research. This new field applied mathematics and science to military and naval problems. Analysis of aerial attacks on U-boats had shown, for example, that many submarines were escaping damage because the depth bombs exploded too deeply; when the setting was reduced, the kill rate went up. The Admiralty’s Operational Research Group had also calculated that a convoy twice as large as another one could be given the same protection with only one-third again as many escorts. In other words, a convoy of forty-eight
ships could be as well protected with eight escort vessels as a convoy of twenty-four with six: in both cases the escort vessels would be 2 miles apart.

Five warships were to accompany SC 127, and by 1
P.M.
on the day of sailing their leader, His Majesty’s Canadian Ship
Dundas
, was steaming on the port side of the convoy on a course of 122°. Escort was needed from the start because U-boats had audaciously sunk ships not only in the shadow of the Canadian coast but within the Gulf of St. Lawrence itself. The convoy’s commodore was a Royal Navy Reserve officer, W. van den Donker, master of the S.S.
Empire Franklin
. So SC 127 set out to bring her precious goods to Great Britain, heading southeast by east under a blue sky, on a calm sea, fanned by a gentle breeze from starboard, with visibility only 6 or 7 miles but with the barometer rising.

In Berlin, Hitler’s staff increasingly recognized that Nazi Germany needed to make greater efforts if she was to win this war. The devastating defeat at Stalingrad had impelled propaganda minister Joseph Goebbels to ask of a clapping, shouting audience at Berlin’s Sportpalast, “Do you want total war?” He got back a ringing
“Ja!”
The new armaments minister, Alfred Speer, increased war production. Authorities agreed that they had to cleanse the continent of subhumans; they put into effect the final solution of the Jewish people. And Dönitz, who on January 30 had been named commander in chief of the navy while retaining his post as commander of U-boats, and who now had more than four hundred submarines at his disposal, urged them to hurl themselves like wolves upon the enemy. On April 11, five days before SC 127 sailed, Dönitz told Hitler that his goal was to make the Allies bleed, to sink more ships than they could build.