The Codebreakers: The True Story of the Secret Intelligence Team That Changed the Course of the First World War

by James Wyllie

  Despite Germany’s huge commitment of money and manpower, it was not enough to achieve parity with the Royal Navy, and as the war began, Britain retained a decisive overall advantage, able to deploy 121 cruisers and 221 destroyers against Germany’s 40 cruisers and 90 destroyers. Crucially, in the North Sea, the British had 20 dreadnoughts to Germany’s 13. Closing that gap was nigh impossible: the British had more ships under construction and would continue to produce more than the Germans as the war wore on. The British ships were also faster and armed with heavier guns.

  Many expected the British to capitalise on their superiority by seeking an immediate confrontation with the Germans. Lord Jellicoe, commander-in-chief of the British Grand Fleet, was not so gung-ho. As a veteran admiral with considerable experience of the German navy, he was fully aware of its strengths and had no intention of underestimating his enemy. His strategic thinking was dictated by a realistic assessment of the threat the High Seas Fleet posed, combined with his fear of the sudden and unsuspected destruction that the new weapons of naval war, the torpedo and the mine, could cause: on the first day of the war alone, the Germans laid 25,000 mines in the North Sea.

  For Jellicoe, the preservation of British naval supremacy was paramount. The simplest way to safeguard it was to remain on the defensive and venture out only when necessary; the mere presence of the fleet enough to deter the Germans and maintain the maritime blockade that Jellicoe believed would ultimately win the war.

  Positioned at the entrance to the North Sea and the Channel exits, the British navy exerted a stranglehold on Germany’s overseas trade, cutting it off from the rest of the world. Any ship carrying goods to Germany could be stopped and taken out of commission. By the middle of 1915, nearly half the total tonnage of Germany’s merchant fleet was marooned in neutral ports, unable to leave. Given Germany’s reliance on imports, this was a serious blow: 25 per cent of its dairy, fish and meat came from abroad; its potato crop depended on fertilisers, 50 per cent of which were imported from the USA, Chile and North Africa; while the Americans provided nearly all of its cotton, large quantities of wheat and 60 per cent of its copper.

  Admiral Jellicoe, commander of the Fleet during Jutland and the U-boat campaign

  The Kaiser, reluctant to see his toys get broken, and hoping that his army would deliver a speedy victory, thereby rendering the blockade null and void, initially decided that the High Seas Fleet should remain as close to its bases as possible and not seek battle with the British. This was hard to swallow for many in the German navy, as they knew they were superior in a number of vital areas. Their ships had far thicker protective armour and as a result were less easy to sink; their gunnery was more accurate – in all confrontations with the British, they scored more hits on target; their optical equipment and rangefinders were more advanced and their searchlights more sophisticated, giving them greater capability to fight at night.

  But as it became clear that the ground war would continue into 1915, the German naval high command managed to convince the still cautious Kaiser to let them off the leash a little. The aim was to nibble away at the British Grand Fleet by luring portions of it out to sea and into the arms of the German High Seas Fleet. Over time, operations like Hipper’s assault on Scarborough, the first of its kind, might reduce the deficit between the navies and provide the Germans with the opportunity to engage the enemy in a fair fight.

  The German approach relied on surprise and deception. However, if the codebreakers in Room 40 could supply accurate predictions of the movements of the High Seas Fleet, they would not only deprive it of any tactical advantage but might also allow the British to engineer a situation that allowed them to catch a section of the German fleet away from its bases and expose it to the full force of Jellicoe’s dreadnoughts.

  Not that the Germans lacked wireless interception and decoding capabilities of their own. In late 1914, after army units had picked up and decoded British messages emanating from Dover, the navy decided to get in on the act, establishing their main wireless interception station at Neumünster and forming a deciphering bureau, the Entzifferungsdienst, or E-Dienst.

  At first this was staffed by naval men with no cryptographic experience or talent; only later did they draft in academics. Though the E-Dienst achieved some success, the British naval codes were generally more secure and changed more frequently than the German ones, and the Grand Fleet maintained better wireless discipline while at sea, running silent for most of the time. Critically, the Germans never considered the possibility, despite mounting evidence to the contrary, that their own codes had been broken.

  As the number of interception aerials multiplied, the sheer volume of transcriptions of wireless messages, sent directly from the listening stations, and arriving by tube at Room 40, was becoming hard to handle. Three copies were made of messages that were processed successfully. Those that weren’t – a ‘vast number of fragments … in unknown codes or languages’ – were collected in a large tin, which was labelled ‘NSL’: Not Logged or Sent. In the minds of the codebreakers, the tin took on a life of its own, invading the dreams of one nightwatchman, who woke trembling in a sweat after a nightmare in which he had been put in the NSL and got lost. A constant reminder of what Room 40 was failing to accomplish, the tin soon became an object of hatred.

  This mountain of stuff increased dramatically with the advent of direction-finding stations. Marconi had begun experiments on DF apparatus, which could pinpoint the origin and location of a wireless transmission, as early as 1905, and the results had been tested on a Cunard liner in 1912, but the system wasn’t perfected until 1914.

  The man responsible for bringing DF technology to fruition was Captain Henry Joseph Round, one of Marconi’s key men and a true radio pioneer. With a first-class degree from the Royal College of Science, he joined Marconi in 1902 and achieved breakthroughs in the design of vacuum tubes, cathodes and diodes. By the end of his career he had acquired 117 patents; his work during the war on valve amplifiers vastly improved interception capability.

  Seconded to the army, Round introduced DF stations to the Western Front. Then, in February 1915, he visited Hall at the Admiralty. Excited by the benefits DF could deliver, enabling Room 40 to pinpoint the location of battleships, U-boats and Zeppelins from the wireless signals they sent, Hall ordered Round to erect a station for the Admiralty. A site was chosen at Lowestoft, in Suffolk, and before long the number of DF facilities grew to six, dotted along the UK coastline.

  By now, Room 40 desperately needed more staff. Recruitment was Hall’s domain, and as he acknowledged years later, when drafting his autobiography, the best candidates were ‘men who in normal times would have laughed at the idea that they could ever be of conceivable use to our Intelligence Services’. Hall utilised his social connections and unearthed writers, an expert on furniture and art, and several language teachers.

  His main focus, however, was on academia. Confronted with the problem of having to decide what area of expertise might produce the best codebreakers, Hall concentrated on those with a background in alien languages, modern and ancient, on the basis that they would be familiar with the challenge of untangling the meaning of texts, grappling with unusual terms and syntax, and employing the sort of analytical rigour that codebreaking required.

  One of the new recruits with a linguistic background was Nigel de Grey. Educated at Eton, the son of a rector, and fluent in French and German, de Grey had been working for the publisher William Heinemann before the war. Twenty-eight in 1914, he served in the Royal Naval Volunteer Reserve (RNVR) in Belgium during a doomed attempt to stop the Germans capturing Antwerp. The operation, Churchill’s brainchild, came too late to save the city, and the remnants of the small British force were left to fend for themselves, grabbing any opportunity they could to escape.

  Back in the UK, de Grey was head-hunted by Hall and became one of Room 40’s most important codebreakers. His chief collaborator was Reverend William Montgomery, an expert in medieval German th
eology from Cambridge who had translated several obscure religious texts from that period into English.

  Hall also scoured the universities for suitable individuals with classical training: men like Frank Adcock, future Professor of Ancient History at Cambridge, and Alfred Dillwyn Knox, better known as Dilly. By the general agreement of his Room 40 contemporaries, and those who continued their trailblazing work, Dilly Knox was the most gifted codebreaker of them all.

  Skinny, bespectacled, and original in everything he did, Dilly perfected a style of spin bowling that bamboozled countless cricketers. He produced similar confusion when playing bridge, bewildering his opponents with his choice of cards. Riding his beloved motorbike, he was a danger to himself and others. In 1931, after years defying the odds, he had a serious crash and broke his leg. After that he got a car, an Austin 7, which he drove to High Wycombe station every day to catch the London train. During the 15-minute journey, he would recite Milton, often with his hands off the wheel. Almost nobody wanted a lift from him; one brave resident recalled how Dilly ‘used to amuse himself seeing how far he could go downhill with the engine off’.

  Born in 1884, Dilly came from an ecclesiastical family. His grandfather was a wandering missionary who spent many years in India preaching to the poor and destitute; his father was an Anglican priest, and his mother a Catholic of Norman descent. Two of his three brothers would serve Rome, one as a populist writer and commentator on spiritual and moral issues, the other ministering to the dispossessed of east London; his other brother settled for secular pursuits, becoming a much-admired editor of Punch.

  Growing up, the boys enjoyed inventing games and puzzles, and were obsessed with trains, learning the timetables off by heart and testing each other on them. It’s tempting to think that Dilly’s uncanny ability to hold vast amounts of abstract data in his head and imagine it arranged and rearranged in rows and columns came from studying Bradshaw’s Railway Guide.

  Dilly was seven when the family exchanged the rural parish of Knebworth for the grim, dirty industrial district of Aston in Birmingham, crammed with factories and squalid terraced housing. His father threw himself into his work, and the presence of a railway track at the bottom of their garden delighted the boys, as did the thrill of riding trams round the city. However, during their first Christmas there, his mother came down with flu, and eight months later she was dead. Stunned by this terrible blow, his father packed Dilly off to stay with a widowed great-aunt in Eastbourne.

  There he attended a local prep school, then Summer Fields near Oxford, before earning a scholarship to Eton, where he excelled in mathematics and classics. During the entrance exams for King’s College, Cambridge, he submitted two brilliant papers in Greek and maths, but didn’t bother to complete the others. Nevertheless, they offered him a place.

  By now a pipe-smoking atheist with an interest in amateur dramatics, Dilly came under the influence of Walter Headlam, a brilliant but eccentric classics scholar who never took the right train, once rode a horse into a pond, and only used stamps that he liked the colour of. Headlam’s great project was deciphering, reconstructing and translating Herodas’ Mimes, a series of often obscene satirical dialogues that had been discovered during an archaeological dig in Egypt in 1889 and deposited in the British Museum. This selection of worm-eaten, faded and incomplete papyri had been transcribed by a slave around ad 100, which only added to the difficulties facing scholars who attempted to make sense of them. Undaunted, Headlam was determined to produce a satisfactory edition and enlisted Dilly’s help.

  In June 1908, however, Headlam, always a frail creature, died suddenly at the age of 42. Dilly, having been made a fellow of King’s College in 1909, continued his mentor’s work, travelling back and forth from Cambridge to the British Museum. The job was all-consuming. He had to get the fragments of text in the right order – not easy given that there were chunks missing – fill the gaps where words and letters were absent, use inspired guesswork to account for the copyist’s mistakes, and, as there were no breaks in the script, decide which characters were speaking at any given point in the dialogues.

  Despite these hurdles, Dilly made good progress until the war interrupted his efforts and he joined Room 40. As it turned out, the painstaking process of deciphering Herodas was the perfect training for life as a codebreaker. Almost immediately he demonstrated his instinctive flair for textual analysis by bringing to bear the methodology he’d practised when interpreting ancient Greek poetry. He set about scrutinising less sophisticated German communications, such as weather reports, for any careless errors made by the wireless operators during transmission – inaccurate spellings, short cuts or sloppy habits – that might provide clues to the cipher keys being used in more complex messages. This technique proved effective, and Dilly continued to use it throughout the war, with considerable success.

  After the German navy’s initial attempt to catch the British Grand Fleet off guard during their attack on Scarborough, the next foray by Hipper’s battle cruisers occurred in late January 1915. On the 23rd, Room 40 got wind of it and Churchill was told that ‘these fellows are coming out again … and a raid upon the British coast was clearly to be expected’.

  In fact Hipper intended to lurk near Dogger Bank with the rest of the German High Seas Fleet close by, and wait for the British battle cruisers to arrive, which they duly did. Unfortunately for Hipper, Ingenhol, his commander-in-chief, did his disappearing act again and withdrew, leaving him outnumbered by Beatty’s ships. During an inconclusive engagement, Hipper lost the Blücher but managed to escape further punishment when Beatty, wrongly believing that U-boats were in the vicinity, did not pursue his prey.

  Despite once again proving its worth, Room 40 was generally regarded with suspicion by naval personnel. What could a bunch of civilians possibly know about the complexities of war at sea? Clearly, during the first few months of the war, this was a valid concern; as Denniston freely admitted, ‘of naval German, of the habits of war vessels of any nationality, they knew not a jot’. Schoolboy errors were made that seemed to confirm the prejudices of the Operations Division, whose job it was to interpret Room 40 material. On one occasion, Room 40 reported on the movements of a German ship, the Ariadne, which had in fact been sunk a few weeks earlier.

  Incidents like this gave the Operations Division every excuse to exclude Room 40 from decision-making. When the codebreakers asked for a flagged map of the German coastline, the Operations Division refused. As Denniston caustically observed, ‘no attempt was made to develop the intelligence side of the work’.

  Blinker Hall was the first to recognise the problem and take steps to address it. On 16 November 1914, he appointed a naval expert, Captain H. W. W. Hope, to act as Room 40’s guide and improve their intelligence analysis. With the volume of intercepted messages increasing and the direction-finding network expanding rapidly, Hope was able to put his knowledge to good use. Luckily, the Germans made life easy for him, as he was happy to acknowledge: ‘experience showed that the Germans were exceedingly methodical in their methods and a large number of routine signals were made day after day, which were of great assistance’.

  This accumulation of data gave Hope and his team ‘a good working knowledge of the organisation, operations and internal economy of the German fleet’, and he was proud of the fact that nothing out of the ordinary happened without some kind of warning. Though Room 40 had begun as a skeleton crew struggling to come to terms with the unique language of naval warfare, it had in a short time become a well-oiled machine with an intimate knowledge of the enemy.

  However, this transformation was not reflected in the processing of its intelligence. Decodes were still handed over with minimum comment to the Operations Division; there they were scrutinised by Henry Oliver, Chief of Staff, who personally decided what to show the Admiralty top brass, who then agreed amongst themselves what to tell their boss, Admiral Jellicoe.

  Frustrated by a system that often meant he received important decodes to
o late or not at all, Jellicoe asked for the material to be sent directly to him. His request was denied. The negative consequences of sticking to a procedure set up in the first few weeks of the war, when Room 40’s potential was an unknown quantity, would be fully felt in 1916 at the Battle of Jutland, one of the largest naval actions in history.

  But for now, all attention was focused on the German U-boat campaign under way in the Atlantic, where the Kaiser’s submarines were sinking large quantities of British shipping and threatening to sever the vital trade link with America.

  Chapter 3

  DEATH ON THE ATLANTIC: THE LUSITANIA

  The potential impact of Germany’s U-boats was severely compromised by the rules of maritime engagement. Under international agreements, submarines approaching a civilian vessel were required to announce their presence and confirm without a shadow of doubt what the ship was carrying before engaging it. This procedural limitation blunted the U-boats’ offensive capability.

  In early 1915, after much heart-searching and head-scratching, the Germans took the fateful decision to ignore these conditions and embark on unrestricted submarine warfare against vessels sailing in waters around the British Isles (except for a route north of Scotland): no warnings, no special pleading; any boat was fair game if the U-boat commanders suspected its cargo included war material, whether it be food, raw materials or weapons. The discretion to sink a ship, neutral or otherwise, was theirs.

  It was a gamble, and a dangerous one. The chances of avoiding collateral damage while prosecuting an unrestricted submarine campaign vigorously enough to attain Germany’s goal of forcing Britain out of the war by crippling its trade with America were slim. The risk that civilians would become casualties was high. The unknown quantity was how America would react if German U-boats attacked American interests. As far as the Germans were concerned, it was a risk they had to take, for ships leaving neutral American ports were bringing war supplies to Germany’s enemies, so the submarine warfare policy, Germany hoped, would act as a deterrent to the USA, and not a provocation.