This complacent view changed radically when, shortly after the start of hostilities, a handful of submarines skulked through the less than hermetically sealed blockade and made a harsh impression on both the Admiralty and the British psyche. On September 3, 1939, a lone U-boat managed to sink the liner SS Athenia on its way from Glasgow to Montreal, with some 1,420 on board. More than a hundred passengers perished that day, including the first Canadian to die from enemy action in the Second World War, ten-year-old Margaret Hayworth.8 The loss of the Athenia and the child’s death deeply affected Canadians. Newspapers publicized the story widely, some calling it “Canadians’ rallying point.”
Two weeks later, submarine U-29 sank the British aircraft carrier HMS Courageous, an event surpassed only by the actions of Günther Prien, who, on October 14, slipped his U-47 into the home of the British fleet at Scapa Flow in the Orkney Islands in Scotland and, under the nose of the Royal Navy, sank HMS Royal Oak while at anchor. Churchill, now in his second stint as First Lord of the Admiralty, was apoplectic. One way to avoid catastrophe at sea, he then astutely realized, was to revive the ability British intelligence had possessed in the First World War to read enciphered German naval messages in order to reveal U-boat locations and, with luck, their plans for attack well in advance of first contact.
Ultra or, as it was originally known in naval circles, Special Intelligence, was initially dismissed by British naval commanders, who either misunderstood its vast potential or were ignorant of its past success. Relying on conventional and less profound sources of intelligence, such as aerial photographs, prisoner-of-war interrogations, naval attaché reports and traditional espionage informants, or forgoing it altogether, they blundered into a series of disasters in 1940 that thrust Special Intelligence back into the limelight. The first came in April, when decrypted traffic clearly showed the German interest in Norway; this intelligence went for naught, leading the British and French to engage in a series of costly and ultimately futile actions that paved the way for Hitler’s conquest of that resource-rich country. The next disaster was the sinking of the lumbering aircraft carrier HMS Glorious and her two destroyer escorts at the hands of the German battle cruisers Scharnhorst and Gneisenau. Despite warnings from Bletchley Park’s Naval Section that the two predators had left German ports and were now on the prowl, the Glorious was left to their mercy on her journey home from Norwegian waters.
But worse was still to come. By the fall of 1940, after the rapid German advance through Norway, Denmark, Holland, Belgium and France, the Kriegsmarine was able to establish a presence along the entire coast of Western Europe, from the Arctic to the Bay of Biscay—a position never seriously considered by the Admiralty, and one that clearly threatened British survival. Luftwaffe aircraft and German U-boats could now reach the sea lanes around the British Isles, and their surface raiders could hide in French ports if they chose to break out of their North Sea or Norwegian ports past the now-crumbling British blockade. The French fleet, which the British had counted on to provide additional escort vessels for its merchant-ship traffic, surrendered to the Germans soon after the Italians declared war on France and England in June. Almost overnight, these events extended the Royal Navy’s area of responsibility and stretched its resources to the limit, if not beyond. The Admiralty now had to contend in the Mediterranean with the Italian navy, which was endangering the Suez Canal and British holdings in Egypt and the oil fields in the Middle East. Moreover, on the other side of the world an increasingly belligerent Japan, taking advantage of France’s demise, was making aggressive moves in Southeast Asia that threatened to spill over into the Indian Ocean, cutting Britain’s lifeline to its Far East resources. Even more worrying, back in the English Channel, reports indicated ongoing preparations for a German amphibious invasion of England under the code name Seelöwe (Operation Sea Lion).
By October 1940, when Commander Ian Fleming was waiting in vain for Operation Ruthless to produce results, Great Britain had reached the lowest point in its history. At night, bombs rained down on British cities; by day, what was left of the British army units that had escaped from Dunkirk in June attempted to re-form and rebuild their depleted ranks, augmented by the Home Guard units that, for lack of weapons, drilled with broomsticks while expecting a German invasion at any moment. In London, plans went into effect to evacuate children, treasure and the British government to safer locations in the countryside or in other parts of the Empire, and to continue the fight even after the first Nazi jackboot landed near Dover. On the high seas, during this “Happy Time,” as the German U-boat crews ghoulishly called it, increasing numbers of German submarines armed with potent torpedoes sent hundreds of thousands of tons of merchant shipping and their precious cargoes to the bottom. Meanwhile, seemingly indestructible German super-battleships—Bismarck and soon Tirpitz along with other formidable surface raiders—sat poised to pounce from their lairs and join the feeding frenzy. The overstretched and beleaguered Royal Navy and RAF were the last lines of defence. With England’s survival hanging in the balance, breaking the Enigma codes was seen as nothing short of essential.
The failure of Ruthless and the subsequent postponement of further attempts struck through the hearts of the cryptographers labouring in the huts at Bletchley Park. “Turing and Twinn came to me like undertakers cheated of a nice corpse,” Frank Birch, who had served in both the Royal Navy and Naval Intelligence in the First World War and who now headed Bletchley’s Naval Section in Huts 4 and 8, wrote to Fleming. “The burden of their song,” he continued, was the “importance of a pinch.” Did the authorities in the Naval Intelligence Division realize, he asked despairingly, that without a pinch “there was very little hope of their deciphering current, or even approximately current, Enigma for months and months and months—if ever”?9 With the backdrop of the war at sea ever present in their minds, the cryptographers had toiled and struggled in vain to produce a breakthrough in decrypting the naval Enigma machine. Fleming reassured Birch that they “needed to have no fear that the value of a pinch was underestimated.”10
The magnitude of all these developments in Europe and the Mediterranean, as well as at home, caught the Admiralty off guard. Nothing since the days of Napoleon Bonaparte had posed such a potent threat as the Axis air force, surface fleet and U-boat menace did now. For the British government, the ability to monitor an opponent’s plans, intentions, capabilities and movements well before any action was under way was of prime concern, particularly for the Royal Navy. In naval warfare, the key feature that more often than not determines victory or defeat is surprise. With its resources stretched to the breaking point, the Admiralty could not afford to keep watch in the physical sense on all parts of its empire, and it now needed to develop and maintain a highly accurate intelligence weapon to ensure a cost-effective approach to imperial defence. Accurate insight into the enemy situation would allow the Royal Navy to effect an “economy of force,” positioning its assets wisely around the globe and eliminating, or at least reducing, the odds of overspending in one area or being caught short in another.
To this end, the Admiralty spared little expense in developing the capability to monitor the Kriegsmarine’s situation daily or even hourly, through cryptography and its “poor relations” in the signals intelligence family—direction finding, or DFing (establishing the direction from which a received signal was transmitted); radio finger printing, or RFP (identifying a transmitter by photographing its wave form); and traffic analysis, or TINA (analyzing the characteristics of the radio operator himself).11 Intelligence defined the command structures and orders of battle among the Admiralty’s enemies and could tap into the minds of their rivals—Kriegsmarine commander Erich Raeder and U-boat fleet commander Karl Dönitz, among others—gauging their strengths and weaknesses and the way they intended to play the game.
From various forms of SIGINT—signals intelligence—the staff at the Operational Intelligence Centre (OIC), located in the brown bombproof bunker connected to the Admi
ralty Citadel in London, could infer the number of enemy vessels in repair or under construction and project when and where they would make an appearance on the high seas. They could discover, often in advance, new technological developments that might swing the naval balance of power. Perhaps most important, in general terms they could locate and track surface raiders and U-boats from their bases right across the Atlantic Ocean, revealing where the giant surface raiders Bismarck, Tirpitz or others might suddenly appear or where U-boats were gathering in wolf packs to attack oncoming Allied convoys bringing vital supplies to wartime Britain. This same information, relayed by the OIC to the convoy’s command with a simple “change course to …” message, allowed them either to scatter, in the case of raiders, or to sidestep the submarines lying in wait.
Within the mysterious world of naval intelligence, where signals intelligence reigned as the most vital of all intelligence sources, a pecking order developed. Ultra, a subset within SIGINT, dominated during the first half of the war. Reports from human sources—aerial photographs, traffic analysis and radio finger printing—which suggested that something was stirring with a particular vessel or group of vessels, were helpful and sometimes adequate, but Ultra went farther because it could provide direct or indirect information about Nazi Germany’s intentions and capabilities, sometimes in great detail. When it was available, Ultra provided the most accurate and consistent form of intelligence, and in this sense it was priceless.
Fortunately, by the early months of 1941, Ultra did triumph—and it did so because of the changing nature of naval warfare. Unlike its army or air force counterparts, which restricted the use of the Enigma device to the upper echelons of high command, the Kriegsmarine relied on Enigma-encrypted communications for almost all classes of ships and its multitude of shore facilities. With the war at sea controlled for the most part by wireless communication since the turn of the century, the world’s navies strove to develop codes and ciphers to protect their top secret communications from enemy cryptographic efforts. The seemingly impregnable Enigma machine appeared to be the answer for the German navy. Almost every vessel in the fleet was outfitted with this device—from their super-battleships, pocket battleships, cruisers, destroyers, torpedo boats and U-boats right down to their minesweepers, E-boats, R-boats and flak ships, as well as their anti-submarine and weather trawlers. They all enjoyed the anonymity of Enigma-encrypted communications not only with each other but with shore-based facilities as well. And it was this wide distribution that offered John Godfrey and Ian Fleming such fertile ground from which to pinch the materials so badly needed by the cryptographers at Bletchley Park.
The Enigma machine came to obsess anyone involved with decryption, no matter how marginal the association. It was an intellectual Everest, enticing, taunting, and at times seeming to ridicule its opponents as no other technology in existence had done. It posed impossible riddles and engaged some of the finest minds in England. It led to nightmares, emotional and psychological breakdown, and universal frustration; yet, given the secrecy surrounding it, for decades only muted glory came to those who eventually conquered it at Bletchley Park.
Originally designed in the closing months of the First World War by Arthur Scherbius, a German engineer, for commercial use to protect banking and industrial secrets, the aptly named Enigma encryption device was indeed a riddle, and it soon drew the interest of the German armed forces in the interwar period. Physically, the machine resembled a portable typewriter with a keyboard, a plug board, an illuminated lamp board, and a set of three (later four) rotors that protruded through the top, giving the appearance of a large combination lock. The machine could encipher each letter of the alphabet individually, as opposed to other machines and forms of encryption that encoded complete words, word for word. The Enigma machine was far more subtle and therefore more difficult to crack. It did not actually transmit messages itself, as a wireless or telegraphy set would do. Rather, it scrambled or enciphered each letter of each word of a message into unintelligible gibberish, before transmission to a recipient via wireless. The recipient then deciphered the received message letter for letter using an identical Enigma machine set to exactly the same specifications.
Early in the 1920s, the Enigma machine had made its commercial debut on a limited basis. It was sold domestically on the premise that its contrived internal set-up was so complicated that, should it fall into the wrong hands, it would remain impregnable unless that person also possessed the current setting sheets displaying the exact configurations of the rotor wheels and the plug-board settings that changed daily. The beauty of these code sheets was that, with these materials in hand, the machine was foolproof, allowing any secretary, clerk and, later, private or naval rating to encipher material quickly and accurately after a modicum of instruction. The staggering number of variations of ciphered text that could be produced was virtually unlimited and became the machine’s main selling feature. As one account later claimed, it could encipher “every book on earth … differently without the machine settings having to be repeated.”12 By 1926 the German navy, followed quickly by the army, saw Enigma’s massive potential benefits and adopted it wholesale, with each service improving on the basic design, particularly once the Nazis came to power.
The version employed by the Kriegsmarine was more complex than the German army’s version of Enigma. Housed in a square wooden lidded box that resembled a silverware case stamped with the trademark Enigma, the machine required only three rotor wheels but offered eight removable wheels in all, each of which had its own distinct electrical wiring.13 These wheels formed the basis of the multi-layered or multi-step design that proved the hallmark of its security. When the signals operator wanted to begin transmission of a message, or to receive one, while at sea or on shore, he needed to consult a bigram table and a key sheet that contained what we would today call the daily “password,” or “pin” number.
The three-wheel Enigma machine in its wooden carrying case (the trademarked moniker ENIGMA stamped on the inside front panel and the German instructions in the lid), ca. 1930s. In addition to the main keyboard with its raised keys, it has a plug board (bottom), three rotor wheels (at the back, behind the keys), and an illuminated lamp board (top). (photo credits 3.1)
Two sets of spare rotor wheels for the three-wheel Enigma machine, in their carrying box. With each rotor wheel designed with its own unique electronic wiring system, these wheels were at the top of the list as targets for pinch operations during the first phase of the war.
The Three rotor wheels laid out on their sides. The alphabet is visible around the edge of the top rotor wheel. The three central rotor wheels were selected from a box of five for the army and air force versions of the machine and eight for the naval version. Monthly orders listed on key sheets, tables and code books specified a new combination every day (A-B-C, E-G-H) as well as their relative order in the machine (II-IV-V, III-I-IV), etc. (photo credits 3.2)
In the first step, the bigram table produced a random letter set known as the indicator. This set was sent as the plain-text heading of the enciphered message to instruct the receiver how to set up the machine. The next step involved the daily key setting, which usually came every month in the form of a booklet, called a K-book, or in a set of sheets and tables printed in water-soluble ink. This information was issued to both the senders and the receivers of messages. To make sure they were on the same page, all the operators on a given network, after receiving the indicator, consulted these materials to establish the starting position of the machine—specifically, which three of the eight possible rotor wheels to insert into the naval version of the machine, and in what order to place them in the slots at the top. Each rotor wheel was wrapped with a removable rubber ring with letters of the alphabet stamped on it, which was then clipped in a preordained position, also listed in the key sheets. The operator turned each rotor wheel separately until they all reached the given starting position for the day listed on the key sheet. With each wheel corr
esponding to a letter of the alphabet, the operator then lined up the letters, as if lining up the numbers of a combination lock, to produce the key setting itself.
At this point yet another security layer appeared: the operator inserted the plug cables—similar to patch cords on a TV or sound system—into the plug board at the base of the machine in a particular configuration provided by the daily key sheet or, sometimes, to strengthen security, by a completely separate key sheet. That done, the operator was ready to type the text message he wanted to send on the keyboard directly connected electrically to the rotor wheels, which in turn were connected to the lamp board. On the lamp board was another alphabet, as on the keyboard, but the difference was that each letter lit up once the machine was in operation. With every punch of a key, an electrical pulse would race into the individual wiring of each rotor and turn the right-hand rotor one position, to select in random fashion another letter of the alphabet, which would appear in illuminated form to replace the plain-text letter in the original message. With each keystroke, the rotor would turn, providing another unique encrypted letter for the operator to note and write down—by all these means eventually creating an encrypted version of the formerly plain-text message. The message was then transmitted via wireless using Morse code.
When the message arrived, or was intercepted, it seemed to be unintelligible nonsense—unless the receiver had the corresponding key or password to unlock the true meaning of the message. With the key sheet in hand, the receiver proceeded in reverse steps, using his Enigma machine to decrypt the message and reveal its meaning in plain German text.14
To pry into an Enigma-enciphered message, cryptographers had to establish the machine’s configuration, then which three of the eight wheels were in use, the clip position of the rings, and the setting of the three-letter key. Once that was done, they had to figure out the configuration of the plug board. Complicating this task was the fact that each service possessed its own keys and constantly introduced more keys and networks after every victory in Europe or every security scare. In 1940, for instance, the Kriegsmarine employed one basic key for Home Waters traffic, which it called Heimisch, or later Hydra, and which the British code-named Dolphin. After the German invasion of Western Europe, the navy branched out into more keys. By mid-1941 it had separate keys to denote Norwegian, Baltic and Mediterranean traffic. Eventually the U-boat fleet had its own unique key, code-named Triton by the Germans and Shark by the British, along with two special derivative keys that officers and staff (Offizier and Stab) used for highly sensitive messages. To complicate matters still more, each key could have further security precautions attached: there might be special instructions for different internal settings for the staff, in contrast to operational command, or even separate plug-board settings for individual commands or commanders.
One Day in August Page 7
