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

by James Wyllie

  As a consequence, the Zeppelins continued their grisly work without loss. On 5 March 1916, Hull’s waterfront and docks were attacked. The damage was considerable and the commander of the raid ‘saw whole structures toppling into ruins until that section took on the appearance of an immense black crater on the snowy landscape’. Like other targets in the north, Hull was practically defenceless: no guns or planes were available to meet the threat. Afterwards, an angry mob stoned an RFC vehicle and attacked one of its officers. A few weeks later, a terrible tragedy unfolded in Cleethorpes when a bomb landed on a Baptist chapel full of soldiers, leaving 32 dead and 48 injured; a member of the medical team that arrived on the scene likened it to Dante’s ‘Inferno’.

  During July, poor weather prevented a series of raids; then, on the night of 2–3 September 1916, came the biggest one of the war so far, involving 16 airships that ranged across the country, targeting Nottinghamshire, Lincolnshire, Hertfordshire, Sussex and London. However, what might have been another deeply dispiriting few hours of indiscriminate, unopposed carnage proved to be the night the tables turned.

  The technological breakthrough that made the difference was the work of a New Zealand engineer, and came in the form of an explosive soft-nosed bullet loaded with phosphorus that flattened on impact, creating a large hole. Used in combination with incendiary bullets and tracer bullets, known as ‘sparklets’, they finally gave the air force the means to cause significant damage.

  During the Saturday night in question, 2/3 September, SL11 was shot down at Cuffley Hill in Hertfordshire. News that one of the beasts had been slain was greeted by a wave of euphoria, a great release of accumulated stress and tension. The next day became ‘Zeppelin Sunday’. Special trains were laid on from King’s Cross to ferry curious and jubilant crowds to the crash site. The landlord of the local pub charged twopence entry.

  One of the first visitors to inspect the wreckage was Blinker Hall. In May, the Germans had changed their code books. The HVB, used by the Zeppelins, was replaced by the Allgemeines Funkpruchbuch (AFB). For the first time, Room 40 was operating in the dark. Hall was desperate to get his hands on a copy of the new codes, especially as they were being adopted by the enemy’s submarines as well. Until he did – and there was no guarantee that he would – Room 40 had no alternative but to begin the painstaking and laborious business of trying to reconstruct the AFB codes from scratch by trawling through the plethora of available messages for clues.

  The obvious choice for this task was Dilly Knox, now firmly established as Room 40’s leading codebreaker. By early 1916, Dilly had his own office, Room 53, a tiny space dominated by a huge desk and a bath that he had had specially installed. Lying in a steaming tub for hours helped stimulate Dilly’s thought process as he pondered codebreaking conundrums. Though his work was often presented ‘in inky scribbles on sheets of dirty paper’, sometimes sopping wet from bathwater, there were no doubts about his ability.

  With nothing to go on except messages sent in the new code, which consisted of three-letter groups, Dilly, searching for an identifiable pattern, noticed that the word ending ‘en’ was repeated throughout in a similar position. He realised that this construction resembled a poetic metre known as dactyls. This suggested to him that the wireless operator responsible had encoded his signature, which identified him as the sender, by using part of a poem.

  Dilly was no expert on German literature, so he took the messages to someone who was: Professor Leonard Willoughby. Willoughby examined them and decided they came from a poem by Schiller. He gave Dilly the full translation of the relevant lines, and armed with these Dilly was able to identify ten new code words, which he used as the basis for further reconstruction of the AFB. Nevertheless, it might take months for him to crack the whole thing open.

  The best hope of resolving the crisis, therefore, was for Hall to recover a copy of the code book from a downed Zeppelin. When SL11 met its doom on 3 September, he was ready to act fast. According to Hoy, ‘Hall rushed to the scene as soon as the news of the fall of the blazing Zeppelin reached him, but by the time he reached Cuffley, the wreckage had burned itself out.’

  Then, three weeks later, during another massive assault, L33 was hit several times after terrorising the East End and landed in a field near Chelmsford. Miraculously, both ship and crew survived intact. Having destroyed their code books, the men wandered to a village and were taken in by local police. That same night, 23–24 September, L32 was shot down at Snail’s Hill Farm near Billericay in Essex. A fellow Zeppelin commander described the moment it was hit: ‘suddenly a red light shone out vividly through the darkness … a vast ball of fire hung in the heavens … and then like a gigantic torch, the ship dropped faster and faster to earth. She crashed to the ground and continued to burn … our grief was overwhelmed by horror.’

  Trooper Charles Williams was one of those assigned to guard the wreck, which ‘burnt well into the early hours of the morning’. The roads leading to it were jammed with cars and people keen to get a look. By dawn, thousands had gathered. Williams and his fellow soldiers made a tidy profit selling bits and pieces of the wreckage, while local blacksmiths converted scraps of metal into bespoke souvenirs.

  Hall was also on the hunt for mementoes from the remains of L32. He had a team on site before the other scavengers arrived and they were rewarded for their efforts. The new code book, somewhat charred, was retrieved from the smouldering remains.

  From that point on, the law of diminishing returns applied. In the next six months, four more Zeppelins went down in flames. A further seven crashed in the sea. Not a single crew member survived. Another Zeppelin was blown up by RNAS planes during a bombing raid on its sheds at Trondern: this attack was the first ever air strike launched from a ship, HMS Furious. The aircraft carrier was born.

  Though new Zeppelins were being built, the loss of so many highly experienced personnel was much harder to bear. The final blow was a self-inflicted wound. On 18 January 1918, a terrible fire broke out at Ahlhorn, the main Zeppelin base. Five Zeppelins were destroyed. An assistant mechanic recalled the destruction: ‘I heard the benzine tanks explode, the flames crackle, the girders break and the glass burst.’ Next morning, he surveyed the damage: ‘I saw the lean iron ribs of several sheds standing out like leafless trees in the wintry sky. Ahlhorn had simply been wiped off the earth.’

  The last attack on London was on 19 October 1917; only one Zeppelin, L45, got through. The Midlands, the north and East Anglia suffered four attacks during 1918. Wigan bore the brunt of a five-Zeppelin assault on 12–13 April. The local paper reported the death of a woman in her bed: ‘a fragment of the bomb or splinter shot across the room, cut away her face and killed her instantly’. The final attempt was made on 5 August 1918. Returning empty-handed due to bad weather, Paul Strasser, the leader of the naval Zeppelin fleet, and his ship, L70, were consigned to a watery grave.

  Over the course of the campaign, there had been nearly 80 raids – 26 of them on London – causing 557 deaths. Had the German incendiaries been more efficient, the toll would have been much higher. As it was, Britain was faced with a new menace, the Gotha bombers, conventional planes that threatened even more havoc. Unfortunately, the codebreakers were unable to predict their arrival, as they only used wireless on take-off, thereafter maintaining radio silence.

  The first major assault came on 4 July 1917. The authorities reacted quickly, setting up a body called the Air Organisation and Home Defence Against Air Raids under the leadership of the dynamic South African Jan Smuts. It introduced a 45-minute early-warning system, linked to 80 fire stations within a 20-mile radius of Charing Cross. During eight days in late September, known as the Blitz of the Harvest Moon, the Gothas dropped 5,000 kg of bombs, killing 69 people. Nearly one million Londoners sheltered in the Underground. Others slept in parks and fields or simply left the capital. But the air force’s improved armaments inflicted mounting losses on the Gothas, which at this late stage in the war the Germans could not affor
d to sustain, and the raids slowly petered out. Overall, through trial and error, invaluable lessons had been learned that could be applied next time Britain faced death from the skies.

  PART II

  Chapter 9

  CORRIDORS OF POWER

  In the early 1930s, Blinker Hall, with the help of a ghost writer, embarked on his autobiography. In the few chapters that survive from this unpublished work – it was killed stone dead by the authorities – Hall claimed that under his guidance, naval intelligence ‘grew … into an almost worldwide organisation with a multitude of the most diverse activities’. This was no idle boast. His power and influence spread far and wide; nothing was out of bounds. Any action he thought would help bring victory was legitimate. He didn’t care about ignoring the chain of command or stepping on other people’s toes. Nor did he mind if his actions were morally or legally dubious, or carried considerable risks; as he put it, ‘I came to the decision that if we were to get on with our job, there must be no slavish regard for peacetime precedents.’

  Almost immediately he proved true to his word. The issue he addressed head on was that of postal interception: the opening of suspect mail. In 1911, when Churchill was Home Secretary, the system was very limited: a warrant had to be obtained for each single letter or telegram that the security services wanted a peek at. Churchill adjusted the law so that warrants covered all the mail received by suspicious individuals.

  Nevertheless, in autumn 1914, there was only one censor at London’s Mount Pleasant sorting office, and a few overwhelmed staff. One clerk admitted that only 5 per cent of the post was being dealt with, the rest piling up in cupboards. Once Hall was made aware of the situation, he felt ‘it was imperative to enlarge very considerably the existing scope of censorship and to press for its rapid extension’.

  He paid a visit to the man in charge and told him he wanted ‘to make sure that all the foreign mails are opened and that no secret message gets through’. Without bothering to ask for permission, he got hold of 200 men, all volunteers from the National Service League, squeezed £1,600 from Churchill on false pretences, and put these resources to work on a two-month trial basis. He quickly realised that the Germans were ordering contraband goods via the post, thereby defying the blockade.

  Hall’s meddling nearly blew up in his face. After a few weeks, a troublesome MP who was already under scrutiny discovered his mail was being interfered with. Outraged, he complained to Reginald McKenna, the Home Secretary, who demanded to see Hall, warning him that the sentence for tampering with His Majesty’s mail was two years in prison.

  With his career hanging by a thread, Hall was sent to Asquith, the prime minister, at 10 Downing Street. Though by the end of the war he had met a great number of politicians and ‘seen to some extent how their minds worked’, it was his first visit to this august address and he felt distinctly nervous: ‘once inside this rather shabby old house I could not rid myself of the idea that I was only witnessing some strange kind of stage play. Things had suddenly become unreal.’ Luckily for him, Asquith was in favour and endorsed his actions. By the end of the war, 4,801 staff, mostly women, were engaged in steaming open hundreds of letters a day.

  Hall not only interfered on the domestic front, he was equally willing to take the iniative over international diplomacy. In early 1915, he put into motion an audacious plan to bribe the Turks to sue for peace. The Ottomans’ entry into the war, November 1914, was half-hearted at first, reflecting deep splits in the government over the right course to take. With British warships gathering in the Adriatic, reports were coming in of the uncertainty and fear gripping the population in Constantinople (Istanbul), and Hall spied a chance to exploit these tensions.

  He contacted a British civil engineer working for a firm of contractors, who was ‘on friendly terms with many of the most influential Turks’. Hall’s contact agreed to try and get in touch with Talaat Bey, the Minister of the Interior, who was known to have doubts about the war. In his memoirs, Hall stated that on 5 March 1915, ‘the price offered for the complete surrender of the Dardanelles with the removal of all mines was £500,000’.

  While Hall rolled the dice, Churchill was also prepared to gamble that the Turks would fold if enough pressure was applied. During February 1915, Churchill bullied and cajoled his colleagues into agreeing to try and send ships through the heavily defended Dardanelles and on to Constantinople; once there, the threat of the city being bombarded by their guns might prove sufficient to force the Turks to capitulate. However, the straits were guarded by fortifications armed with heavy artillery and mobile gunnery with enough firepower to prevent easy access and stall the operation.

  Then Room 40 received and decoded two messages that referred to the fact that the Turkish defences, which had so far prevented British ships from getting through, were very low on ammunition and it would take several weeks before more would arrive. Could this be the chance the British were waiting for? Realising that this information might be a game-changer, Hall visited Churchill and Lord Fisher, the Admiralty’s most senior naval figure, and told them the news. Both of them were galvanised by what they heard; the navy might now be able to enter the Dardanelles without sustaining heavy losses. According to Hall, Fisher exclaimed, ‘By God … I’ll go through tomorrow,’ while Churchill ‘seized hold of the telegram and read it through again’ with great enthusiasm.

  Sensing that this was a decisive moment, Hall decided to tell them about the bribe, or as he put it, ‘the large sum of money I had personally guaranteed’. An astonished Churchill asked how much, and Hall replied, ‘Three million pounds … with power to go to four million if necessary.’ Churchill demanded to know who had authorised this offer; Hall responded, ‘I did.’ Alarmed, Churchill probed further: what about the Cabinet? Did it know? Unruffled, Hall replied, ‘No, it does not. But if we were to get peace … I imagine they’d be glad enough to pay.’

  Before Churchill could fire off another question, Fisher, still processing the fact that the enemy was running short of ammunition, declared, ‘No, no, I tell you, I’m going through tomorrow, or as soon as can be completed,’ then turned to Hall: ‘Cable at once to stop all negotiations … We’re going through.’

  Hall bowed to his superiors and took the bribe off the table. The navy renewed its doomed assault on the straits, frustrated as much by the dense network of minefields as by the Turkish guns. After repeated attempts the operation was abandoned and the fateful decision made to conduct an amphibious landing at Gallipoli. The troops involved quickly became mired in trench warfare every bit as harrowing as on the Western Front, with the added discomforts of blistering heat and disease. As the scale of the disaster became sickeningly apparent, both Churchill’s and Fisher’s jobs were on the line.

  The careers of these two colossi had been intertwined for years. Churchill admired Fisher’s dynamism and innovation, while Fisher found Churchill ‘Napoleonic in audacity, Cromwellian in thoroughness’, and considered him ‘a staunch friend’. Nevertheless, the cracks were beginning to show. After the war, and with his characteristic literary flair, Churchill compared Fisher to ‘a great castle that has contended with time’. Hall, more prosaically, agreed that Fisher was ‘a tired man. The strain under which he worked would have been terrific … He might still on occasion show the old flashes of brilliance, but, beneath the surface, all was far from being well … at any moment, we felt, the breaking point would come.’

  At the same time, Hall was acutely aware that Churchill ‘had the defects of his great qualities. He was essentially a “one man show”. It was not in his nature to allow anybody else to be the executive authority.’ He recalled an incident where they were debating an issue from diametrically opposed points of view: ‘it was long after midnight and I was dreadfully tired, but nothing seemed to tire the First Lord. He continued to talk and I distinctly recall the odd feeling that although it would be wholly against my will, I should in a very short space of time be agreeing with everything he said.’ Battere
d into submission, feeling his own sense of self diminishing rapidly, Hall admitted defeat: ‘I can’t argue with you; I’ve not had the training.’

  Admiral Jackie Fisher, 1914

  Not surprisingly, both Churchill and Fisher had their enemies. Working in harmony, they could deflect the critics and backbiters, but once serious differences over the Dardanelles campaign surfaced, they became vulnerable. In a fit of pique, Fisher offered his resignation. Churchill, knowing that this could spell doom for him as well, immediately wrote to Fisher on 15 May: ‘if you go at this bad moment … thereby let loose upon me the spite and malice of those who are your enemies even more so than mine’. Fisher was unmoved; he reminded Churchill that he had been ‘dead set against the Dardanelles operation from the beginning’ and reaffirmed his decision to ‘GO’.

  At this critical juncture, Hall was asked to act as assassin by Sir Frederick Hamilton, Second Sea Lord. Senior figures within the Admiralty felt the time had come for both Fisher and Churchill to step down: the Dardanelles campaign had been Churchill’s baby, which he’d pushed through despite serious concerns about its value. Now, as the hard-pressed British were having to commit more and more resources to landings at Gallipoli that had only become necessary because of the failure of the navy to do its bit, Churchill had nowhere to hide. Given that the ageing and autocratic Fisher had returned to the top job because Churchill had insisted on his appointment, it was inevitable that he would be ousted as well.