The Codebreakers: The True Story of the Secret Intelligence Team That Changed the Course of the First World War (32 page)

Working under her was a selection of well-bred, well-connected young ladies, such as Miss Harvey, daughter of Sir Ernest Harvey, secretary of the Bank of England. Not all the women were confined to clerical tasks; a few tried their hand at codebreaking. Miss Henderson, daughter of Admiral Henderson, and Miss Hayler, who worked on Italian non-alphabetical codes, were the best of the bunch.

With the women living in such close proximity with their male colleagues, in an environment charged with tension and excitement, romantic entanglements were inevitable. Alastair Denniston met Dorothy Mary Gilliat and they were married in 1917, while Dilly’s friend Frank Birch fell for his future wife Vera Gage. More disruptive was the presence of Mrs Bayley, wife of a City doctor: according to Clarke, she ‘caused slight but unimportant trouble by her very attractive appearance’. With these remarks he did his best to draw a veil over the truth. Mrs Bayley conducted affairs with both W. L. Fraser and Russell Clarke, the original radio buff.

Dilly’s brother thought that Dilly, owing to his inexperience, ‘would be quite powerless if he was thrown together for any length of time with a normal, pretty woman’ and, sure enough, he found himself falling under the spell of one of his female assistants. Not that Dilly was consciously seeking a partner: his appearance, with his ‘long thin wrists stretched out from the cuffs of a uniform that hung on him like a sack’, and absentminded habit of forever misplacing his spectacles and getting them confused with his tobacco pouch, would have been enough to deter a lot of women.

Not Olive Roddam, daughter of Lieutenant Colonel Roddam, part of an aristocratic Northumberland family descended from Anglo-Saxon nobility, who became his secretary during 1917. Olive would often arrive for work to find him still soaking in his think-tank, and it was in the intimate setting of Dilly’s office that love blossomed. They were married in July 1920. Lytton Strachey, still smarting from Dilly’s rejection of him at Cambridge, responded to news of their wedding with this acid comment: ‘Dilly Knox … is to be married to an undeniable female – poor helpless vanished thing.’

With staff numbers now at an all-time high and Room 40’s intelligence finally being processed efficiently, Hall had every right to feel confident that the U-boat threat would be successfully neutralised. However, the one measure that could transform the situation in the Atlantic was still being ignored until the prime minister, David Lloyd George, deeply frustrated by the intransigence of his naval commanders, descended on the Admiralty at the end of April and gave them a piece of his mind. Why weren’t they using the convoy system? Surely having warships sailing alongside a convoy of merchant ships was the best way to prevent losses?

One of the arguments against convoys was that such a large collection of vessels would make an even bigger target for the U-boats. This proved not to be the case. Of 219 Atlantic convoys that sailed between October and December, only 39 were sighted by U-boats. As Churchill observed, ‘the sea is so vast that the difference between the size of the convoy and the size of a single ship shrinks in comparison to insignificance. There was in fact a very good chance of a convoy of 40 ships in close order slipping unperceived between the patrolling U-boats as there was for a single ship.’

The U-boat captain Karl Dönitz, future head of Hitler’s submarine forces, echoed Churchill’s comments: ‘for long periods at a time, the U-boats, operating individually, would see nothing at all: and then suddenly up would loom a large concourse of ships … surrounded by a strong escort of warships of all types … the lone U-boat might well sink one or two ships, or even several, but that was a poor percentage as a whole. The convoy would steam on.’

The Admiralty had been debating this issue for months without reaching agreement. Lloyd George forced its hand. By the end of May, convoys of between 30 and 40 merchant ships, with a screen of battleships around them, were introduced. To ensure they were given the benefit of Room 40’s discoveries, Hall formed a Convoy Section at NID, where ‘for the first time the latest information about enemy submarines could be placed next to the data regarding convoys. Any intelligence regarding the presence of U-boats could be quickly transmitted to the convoy’s commanding ship, which was always equipped with wireless. This made it possible to immediately divert a convoy from a dangerous area.

Though the decline in losses was not huge, it was significant enough to avert disaster. More importantly, the number of U-boats being sunk increased. Between 1914 and 1916, only 51 were destroyed, but in 1917 the strike rate rose to 75, while in 1918, 102 were disabled. Each time one of them went down, Hall would celebrate with a glass of rum.

This modest ritual gives us some idea of how personally Hall took the U-boat menace. He understood what was at stake: the survival of the Allies as a fighting force. As a result, he put himself, and those around him, under intense pressure to provide what was needed to win his battle with the submarines. Nobody was spared. Even his compatriot Mansfield Cumming, head of MI6, felt the heat of Hall’s displeasure during 1917. In September, Hall, who according to Cumming’s diary was ‘decidedly seedy and irritable’, complained that Cumming’s organisation was ‘not good’.

Cumming was understandably worried that he might lose Hall as an ally. When Hall got his knighthood shortly afterwards – in recognition of his Zimmermann telegram triumph – Cumming used his letter of congratulations to try and smooth things over: ‘I owe you far more than I could ever repay and wish I could serve you better … you have my unswerving loyalty and devotion.’ Still unsure whether the damage had been repaired, he visited Hall on Christmas Day. Aside from seasonal greetings, he told Hall ‘that I regretted very much that he is not satisfied with our Naval information’, and assured him that he was doing his best. Determined to show he meant business, he made MI6 pull out all the stops to get Hall what he wanted. The results speak for themselves. From the start of the war to October 1917, MI6 had produced 260 naval reports; in the year that followed, they produced 8,000.

Slowly but surely, the tide began to turn. The accumulated effect of Allied counter-measures was taking its toll. The Germans, hampered by bottlenecks in the production process and the fact that many of their submarines were tied up in ports for repairs and maintenance, had fewer U-boats available for action. More serious was the loss of veteran commanders: out of 400 U-boat captains, a mere 20 of them accounted for 60 per cent of the damage inflicted. These warriors of the deep were irreplaceable. The balance of power tilted in favour of the Allies.

A varied and constantly improved arsenal was deployed against the U-boats. Depth charges, loaded with 300 pounds of TNT, proved fatal if they landed within 100 feet of a U-boat. The number used doubled in 1917, and doubled again the following year. Their effect was devastating. The American admiral William Sims saw the carnage they caused up close: ‘first, the depth charges exploded, causing a mushroom of water … Immediately afterward, a second explosion was heard; this was a horrible and muffled sound coming from the deep, more powerful and terrible … an enormous volcano of water and all kinds of debris arose from the sea … as soon as the water subsided, great masses of heavy black oil began rising to the surface.’

New, improved mines, based on a German design, went into mass production, while the British got better at minesweeping, with spectacular results: in 1917, 128 merchant ships were lost to mines; in 1918, only ten. Room 40 played its part. The codebreakers had cracked the codes used by German minesweepers and minelayers, enabling them to not only warn against danger but also to monitor the success of British mining operations.

The hydrophone, a listening device that could pick up the sound of underwater propellers, was developed. ‘Dazzle painting’, where ships were decorated in bizarre patterns, was introduced to fox the enemy: nearly 3,000 ships were camouflaged this way. A large number of merchant ships, known as DAMS, were fitted with cannon: 1,749 in 1917, up to 4,203 in 1918. Meanwhile, the Channel defences were strengthened and barriers built to block and entrap the U-boats. Air support was also provided. By the end of the war, there were 285 seaplanes and flying boats, plus 272 land-based aircraft with radios, touring the skies over the Atlantic.

In the USA, a massive construction programme was launched to replace the ships being lost. The American merchant fleet in April 1917 stood at 2.75 million tonnes; by September 1918 it totalled 9.5 million. In the UK, 35,000 skilled workers were pulled out of army service and sent to the shipyards to help with repairs and the construction of new vessels.

While the Atlantic remained Room 40’s priority, U-boat attacks in the Mediterranean were becoming a real problem. In the spring, Hall toured the region, visiting Rome, Malta and Alexandria, and came to the conclusion that ‘the time has come when every effort must be made to assist our joint naval operations in the Mediterranean. The sinkings there … are a matter of grave concern.’ What was needed, among other things, were wireless-interception and DF stations that could track the messages sent by the U-boat hunters.

The man chosen to locate and build these listening outposts was Eric Gill, a professor of physics and fellow of Merton College, Oxford, where he’d run an experimental electronics lab. Gill had joined the army in 1914 and immediately found himself digging narrow trenches on the Isle of Wight to guard against German invasion under the watchful eye of a general who, according to Gill’s witty memoirs, arrived in a large, expensive car. If the trenches failed to halt the advance of the enemy, Gill’s tiny force ‘were to retire to the high ground … and conduct guerrilla warfare’. Other duties included motorcycling round the island to enforce the nightly blackout, which alarmed local poachers and the odd ‘shepherd with a lantern’.

It took the War Office several months to realise that this technical and theoretical expert might be more useful elsewhere. He was invited to apply for artillery training with the Royal Engineers at Woolwich, an experience that he found completely underwhelming. After six weeks of rudimentary instruction, he was summoned ‘for an extremely hush-hush business’ to be conducted at Lord’s Cricket Ground, which turned out to be equally frustrating.

The training there was organised in tandem with the Marconi Company and consisted of a ‘rather odd crowd’ who spent most of the time learning to put up wireless masts as quickly as possible. Anything more sophisticated was out of the question, as the Admiralty had ‘prohibited any transmission of signals and there were none that we were allowed to receive’. Next, Gill was selected for ‘special wireless intelligence work’. This sounded promising until he realised he’d be sharing a room ‘with an elderly officer who was in charge of all the drainage of the British army’. After his talents were finally recognised, Gill spent time masterminding the establishment of wireless facilities in the Middle East before being sent to the Mediterranean.

His first stop was Cyprus. The British government, represented by the Colonial Office, had taken control of the island in 1878, though it remained technically part of the Ottoman Empire. At the outbreak of war with the Turks, it was promptly annexed and placed under military law. During 1916, it was decided that it would be the perfect location for a DF wireless station. Cyprus was ideally placed not only to pick up German—Turkish messages from the Middle East but also to monitor the U-boat threat to Allied shipping.

By October 1917, there were 14 Austro-Hungarian submarines and 32 German ones patrolling the Mediterranean, targeting troop convoys and supply ships vital to the Allied war effort. In April of that year, they sank 254,911 tonnes. In November, the Royal Navy lost seven vessels. During 1918, U-boat attacks in the area accounted for between a third and a quarter of all Allied ships lost.

Locating signals sent by the submarines was no easy matter. Cleland Hoy noted that ‘when they were dodging about in the Ionian and Aegean Seas, they proved slippery customers’. Room 40 might supply intelligence that a U-boat was ‘for instance, off Andros, but though her wireless was working all the time neither we nor the Germans themselves could say where she might be tomorrow. The hundred and one possibilities of the Grecian Archipelago defeated us.’ The hope was that once the DF station was built, it would prove easier to get an accurate fix on these predators.

Gill was delighted with the posting, and thought Cyprus ‘one of the most delectable spots on earth’. However, with a mixed Greek and Turkish population, neither of whom was exactly trustworthy, and an administration overly concerned not to provoke them or upset their sensibilities, Gill concluded that the island was more of ‘a comic opera than anything ever seen on stage’.

The authorities wanted Gill to construct the DF station a quarter of a mile from the sea. Once it was completed, they began to worry that it might be destroyed by submarine. Their solution was to get a gun to protect it. When the artillery unit arrived, they immediately set about moving into a spacious villa. Gill sardonically recalled how ‘all their energies were devoted … to making the house thoroughly comfortable and six weeks after they landed the gun was still not ready for action’. Losing patience, he intervened on the basis that the preparation of the gun’s position was ‘more important than the redecoration’.

Almost as soon as the gun was ready, the officer in charge, worried that German spies might discover its location, ordered the nearby town ‘plunged into darkness every night’. This preventative measure did nothing to stop local fishing boats plying their trade right under the nose of the gun. The officer complained that they might get hit if it turned its attention on enemy submarines. Gill suggested they actually fire it one night to act as a deterrent; the authorities, however, were horrified by the idea, fearing that an unannounced barrage would traumatise the villagers and waste ammunition.

Unperturbed, Gill pressed his case. Finally it was agreed that a test shoot would take place. All the inhabitants of the island were warned in advance. This only served to cause the panic they were hoping to avoid, and the population promptly fled to the hills. To cap it all, when the firing took place, the recoil buried the gun in the earth.