by Alastair Denniston- Code-breaking From Room 40 to Berkeley Street
But the intercepting officers were now learning a lot about the methods of German naval W/T and it was possible to allot aerials to various wavelengths and even districts. Thus the operators soon realised that the Baltic and North Sea Fleets were on different circuits and under different controls. The submarines formed a separate group and the small outpost craft in the Bight yet another. 40 OB learnt these things too and, even at this period, Baltic messages received scanty treatment.54
Room 40 had a number of noteworthy successes during WW1, during which it broke most of the German naval keys. The German Navy had produced charts which divided up the North Sea into numbered squares to identify the position of its ships. Room 40’s first success was reading a message which showed that a German auxiliary ship had been ordered to search for missing torpedo boats in a particular area. Ewing took the information to Oliver (COS), and a cruiser was dispatched and confirmed that the information was correct. Rotter discovered the key being used for the private messages of the German Commander-in-Chief. Messages were telegraphed over a private wire from the intercept stations to the Admiralty and delivered to Ewing’s office. They were then decrypted, translated and if deemed of importance brought at once to the notice of the War Staff. They often led to direct action by the British fleet.
The German High Seas Fleet was usually kept in the safely-guarded river estuaries of the Heligoland Bight behind a minefield and only came out into open waters from time to time for raids. Room 40 had advance notice of most of the actions of the German fleet: messages would order minesweepers to clear certain channels, a lighthouse would receive orders to show its lights for a certain period, orders would be issued for barrier booms to be opened or for aerial reconnaissance. Orders would also be read from the German Commander-in-Chief to squadrons and flotillas giving the composition of the force and its time of departure.
In December 1914, German battlecruisers bombarded Scarborough and Hartlepool. On the afternoon of the 14th, Room 40 had intelligence that the German fleet would come out the next day. Due to bad weather, effective contact was never made by the British fleet, but it convinced the British authorities of the effectiveness of Room 40. Churchill later wrote:
Naturally there was much indignation at the failure of the Navy to prevent, or at least to avenge, such an attack upon our shores. What was the Admiralty doing? Were they asleep? Although the bombarded towns, in which nearly five hundred civilians had been killed and wounded, supported their ordeal with fortitude, dissatisfaction was widespread. However we could not say a word in explanation. We had to bear in silence the censures of our countrymen. We could never admit, for fear of compromising our secret information, where our squadrons were, nor how near the German raiding cruisers had been to destruction. One comfort we had. The indications upon which we had acted had been confirmed by events. The sources upon which we relied were evidently trustworthy. Next time we might at least have average visibility. But would there be a next time? The German Admiral must have known that he was very near to powerful British ships, but which they were, or where they were, or how near he was, might be a mystery. Would it not also be a mystery how they came to be there? On the other hand, the exultation of Germany at the hated English towns being actually made to feel for the first time the real lash of war might encourage a second attempt. Even the indignation of our own newspapers had a value for this purpose. One could only hope for the best. Meanwhile British naval plans and secrets remained wrapped in impenetrable silence.55
Admiral Hugo von Pohl, Chief of the German Admiralty Staff, made a number of proposals to the German Emperor. They included a submarine attack on merchant shipping and ‘sending airships to attack England in the months of January and February, when the weather is suitably calm and cool’. Churchill wrote, ‘So excellent was our Intelligence Service that reports of what was passing in the minds of the German Naval Staff reached us even before Admiral von Pohl’s memorandum had been laid before the Emperor.’56 Churchill’s note to the Cabinet on 1 January 1915 attributed the information to a ‘trustworthy source’.
During 1915 and 1916, Room 40 was able to watch the German fleet and its movements. On Saturday, 23 January 1915, Room 40 read a message from the Commander-in-Chief, Admiral von Ingenohl to the commander of the battlecruisers, Rear-Admiral Hipper, sent at 10.25 am ordering him to scout on Dogger Bank.57 ‘First and Second Scouting Groups, Senior Officer of the Destroyers and two flotillas to be selected by the Senior Officer Scouting Forces are to reconnoitre the Dogger Bank. They are to leave harbour this evening after dark and to return tomorrow evening after dark.’58
They were to proceed to sea that night and to return the next evening after dark. Subsequent decrypts identified the flotilla’s orders regarding the lighting of buoys, the channel to be used to bypass minefields and orders for aerial reconnaissance. Oliver and Sir Arthur Wilson informed Churchill that day and orders went out to the Grand Fleet to prepare to sail. Wilson’s conclusions from the intercepted messages and other intelligence sources were that ‘All the German fast vessels were putting to sea at dark, and a raid upon the British coast was clearly to be expected.’59
A telegram was sent to the Commander-in-Chief with the Grand Fleet at Scapa, to Admiral Bradford with the Third Battle Squadron, to Admiral Beatty with the battlecruisers at Rosyth, and to Commodore Tyrwhitt with the light cruisers and destroyers at Harwich with deployment orders.
They were to meet at a point which would intercept the German fleet before it could reach the Heligoland Bight. The operation wasn’t entirely successful but one ship, the Blücher, was sunk. As each message came in, Ewing delivered it to the War Room of the Admiralty where Churchill, Lord Fisher, Admiral Wilson and Admiral Oliver awaited developments. Early the next morning, Churchill, Fisher, Wilson and Oliver were in the War Room when signals were received that the enemy had been sighted. In the action that followed, according to Churchill: ‘The moment the German Commander discovered himself in the presence of numerous British warships, including the battlecruisers, his decision was taken. He collected his ships, turned completely round, and ran for home with the utmost possible despatch.’60
At 3.45 pm on the 24th, Churchill sent the following letter to the Prime Minister:
This morning Beatty with 5 battle-cruisers and a superior force of light cruisers and destroyers, met Derfflinger, Seydlitz, Moltke and Blücher with light cruisers and destroyers in the middle of the North Sea. The Germans ran for home immediately, and a fierce pursuit ensued, producing a severe action between the battle-cruisers on both sides.
The Lion is damaged, but is returning home at 12 knots. Beatty has shifted his flag to the Princess Royal.
The Blücher (15,500 tons, 25 ½ knots), practically a battle-cruiser, though with 12 8.2 inch guns and 880 men [she actually had 1,200 men on board] is sunk. Two other German battle-cruisers reported seriously injured. Deserting the Blücher, the Germans managed to make good their escape into their own torpedo area, where we thought better not to follow.
He concluded with the comment that ‘Blücher is a heavy loss to the German cruiser fleet – she was only five years old.’
Room 40’s achievement in the Dogger Bank action was summed up by Churchill as follows:
The victory of the Dogger Bank brought for the time being abruptly to an end the adverse movement against my administration of the Admiralty, which had begun to gather. Congratulations flowed in from every side, and we enjoyed once again an adequate measure of prestige. The sinking of the Blücher and the flight, after heavy injuries, of the other German ships was accepted as a solid and indisputable result. The German Emperor was confirmed in the gloomy impressions he had sustained after the action of August 28, 1914. All enterprise in the German Admiralty was again effectively quelled, and apart from submarine warfare a period of nearly fifteen months halcyon calm reigned over the North Sea and throughout Home Waters. The neutral world accepted the event as decisive proof of the British supremacy at sea: and even at home t
he Admiralty felt the benefit in a sensible increase of confidence and goodwill.61
Ewing later reflected on the action from a Room 40 perspective: ‘But on that memorable Sunday of the Dogger Bank action we, who in this strange way were spectators, were left in no uncertainty as to the progress and the issues of the drama. When it was over, the workers of Room 40 could reflect with satisfaction on the contribution they had made.’62
After Dogger Bank, the High Seas Fleet rarely came out until the spring of 1916 when the command had passed to Admiral Scheer, who adopted a bolder strategy. On 25 April, the battlecruisers bombarded Lowestoft but returned to base before the British fleet could intercept them. This and other activity culminated in the Battle of Jutland. Enemy messages, intercepted on 30 May, made it clear that the German fleet was about to set to sea in force. On the afternoon of the 31st, the vanguard of the German fleet encountered, to their surprise, battlecruisers under Beatty and the battle began. At 3.45 pm on 31 May, 1916 Admiral Hipper’s battlecruisers fired the first shots. Intercepted German signals had enabled Room 40 to inform Admiral Sir John Jellicoe, the position, course and speed of the German battle fleet after it had broken off the action. At 9.50 pm, he was told that three destroyer flotillas had been ordered to attack him during the night and at 9.58 pm he was told the position of the rear ship of the enemy battle fleet and that the fleet was on a southerly course. However, this was contradicted by the position he knew the fleet to be in. It turned out that the mistake was made by the cruiser Regensburg, which incorrectly reported its position in the message read by Room 40. But it made Jellicoe nervous about using Room 40’s reports. Further messages renewed his confidence, but an important message from the German Commanderin-Chief was not passed to Jellicoe. The officer who received the intelligence from Room 40 had very little experience of German operational signals and German naval procedure and was not aware of its significance. This was a direct result of Room 40 being restricted to operate as a cryptographic bureau rather than as an intelligence centre. Further decrypted signals flowed to Jellicoe throughout the night. Ironically, they included the disposition of Jellicoe’s forces as seen through German eyes!
In 1916 the Germans changed the key of the principal naval signals every night at midnight, so the night watch played an important role in Room 40. They frequently had solved the new key within several hours, taking advantage of routine messages which provided easy material to aid solution of the key. Another group of stations at Lowestoft, near York, at Murcar on the coast of Aberdeenshire and later at Lerwick provided direction finding information by taking down the bearing of a signal and sending it to Room 40. A big chart would be used to pinpoint the position of the ship that sent the signal. When the Germans started to use the same technique to guide their Zeppelins, Room 40 could use the same information in the intercepted messages to locate them. The technique also helped mask the cryptographic success of Room 40. This was the beginning of naval traffic analysis which, along with military traffic analysis, would prove such a crucial tool for the Allies during WW2.
Given the difficulty of distributing new code books, the Germans relied on keys alone to secure their communications, which proved to be a flawed strategy. Count von Bernstorff, the German Ambassador in Washington, gave evidence about ciphers to a Committee of Enquiry of the National German Assembly after the war and, speaking of the German correspondence with Washington, said: ‘The cipher was not changed as often as would have been the case under normal conditions … To the extent that it was possible to do so, we operated the existing ciphers by means of keys; but I learnt later that the British decoded all our telegrams.’ Hall had feared that the Germans would realise that their signal books were compromised but they failed to change them.
Russell Clarke was now controlling an increasing number of intercept stations. With Marconi-controlled stations also intercepting German signals, the number of messages coming into Room 40 was increasing daily. The civilians operating these stations were placed in a special section of the RNVR called the Shore Wireless Service (SWS). Following a meeting with Captain Round of the Marconi Company, Hall encouraged W/T directional apparatus to be installed in a number of locations to fix the position of a ship or airplane. This enabled Room 40 to obtain by cross-bearings the position of every German ship that sent out a signal. In April 1915, Hall received a copy of the German diplomatic code book. It was used for messages between Berlin and Madrid, and Berlin and Constantinople. The Germans sent messages to their diplomats in North, South and Central America through Madrid. A large number of messages, constructed differently to naval messages, had been previously received by Room 40 and put to one side. By the summer of 1915, progress in reading them was being made. Hall’s political section recruited further staff, with George Young remaining in charge. Young had a wide knowledge of foreign affairs and a flair for cryptography. By October, Young was able to pass on intelligence to Hall about the efforts of the German Government to encourage revolution in India and Afghanistan, both under British rule, and about sabotage in America and the Far East. Hall also became aware of the activities of German agents in the US through these diplomatic messages. One message in April from Arthur Zimmermann, the German Foreign Secretary, to the German Minister in Buenos Aires was a good example of sabotage plans:
It would be desirable to render useless certain particular cargoes of corn, an operation which can be effected, without danger to human beings, by means of doses of KOKODYL or MERKAPTAN contained in GELODORAT capsules. Experiments made here have demonstrated that the capsules can be made to look like grains of corn. They would for this purpose be mixed with the corn when the latter is being shipped from the silos. Two or three capsules would suffice to render 100 kilogrammes of corn offensive to the smell. There is no result until the corn is ground in a mill. You should report whether it is possible to get supplies of the above and to carry out the project.
On 6 May 1916, Ewing was offered the Principalship of Edinburgh University and handed over complete control of Room 40 to Hall. The relationship between the two men appears to have been difficult, caused in part by Hall’s greater understanding of the potential of Room 40. However, Ewing was the founding father of Room 40, the first to recruit staff and through his friend Russell Clarke, responsible for the creation of the Y stations in a very short time.63
In light of German plans to defeat Britain by an unrestricted submarine campaign against merchant shipping, in the autumn of 1916, the operations of submarines became the main concern of Room 40 and the German section under Brandon and Trench. U-boat intelligence was gathered from cryptography, directional wireless plotting, agent reports on the activities in German dockyards, reports of sightings and attacks from convoys and hunting squadrons and interrogation of prisoners. Every shred of evidence was sifted and collated by Room 40.
Room 40 continued to be beset with problems throughout 1916. There was a shortage of staff and while Hope started compiling a card index, assisted by Clarke and Birch, there were no office aids and no typists. However, the main difficulty lay in the separation of its activities from that of Intelligence Division. Ever since the Battle of Jutland, Hall was not happy with the existing system of passing intelligence from Room 40 to the naval Operations Division without comment. However, Operations Division could not be expected to agree readily to intelligence reports from professors and schoolmasters who did not understand the meaning of naval messages. The fault lay in the system in place, in which the senior naval figures such as Oliver, Wilson and Jackson formed their views solely on raw decrypts. Hall managed to convince naval staff that Intelligence Division would benefit from having direct access to Room 40. This was finally put in place at the beginning of 1917. A war diary was compiled and sent daily to the Commander-in-Chief Grand Fleet. Sir David Beatty and individual intercepts were sent with reasoned assessments. The French Admiralty and the Russians (up until the Revolution) were regularly briefed and wounded officers were provided by the War Office to provi
de administration support. Finally, as the war spread to new territories, Hall invited Professors Dickson (Reading), Calder (Manchester), Stevenson (Glasgow) and Henry Marden to prepare handbooks with information about individual intercepts. Room 40 developed special sections dealing with cryptography, the Bight, the Baltic, minesweeping, U-boats, directional, etc.
Staff shortages were addressed at last with the arrival of new staff, including Ernest Harrison, a classical tutor of Trinity College, Cambridge; J.D. Beezley from Oxford; Dr E.C. Quiggin, lecturer in German from Cambridge who then recruited W.H. Bruford and C.W. Hardisty; Edward Bullough, a lecturer in German; L.A. Willoughby, a Taylorian Lecturer in Oxford; G. Waterhouse, a Professor of German from Trinity College, Dublin; F.E. Sandbach from Birmingham; C.E. Gough from Leeds; D.L. Savory, a Professor of French at Belfast; Gerald and Patrick Lawrence, both actors; Desmond McCarthy, an author; G.P. Mackerson, a caricaturist; Father Ronald Knox, Dilly’s brother; Francis Toye, a music critic and author; Edward Molyneux, a couturier; and Frank Tiarks, a banker from Schroeders. Clarke later commented on the new secretarial help provided by carefully-selected young women who were all recommended by an existing member of staff:
Miss Tribe, secretary to Hope, Welsford who insisted on joining up again in 1939, Jenkin now [1953] famous in the BBC programmes, Nugent who went to Chatham House, Mrs Denniston [AGD’s wife Dorothy], Spears, Henderson, daughter of Willie [later Admiral Sir Wilfred Henderson and one of the organisers of the convoy system], Mrs Bailey, who rather upset things with her love affairs, Hudson who came as my secretary and used to embarrass us by her early arrival [when the night watch were still bathing] and was a sister of Hudson, later in the Conservative government and daughter of the soap king, Lady Hambro, as efficient as her husband in the City, who startled Hope at one of our dinners by smoking a large cigar. Curtiss who in my view was the most useful of them all, Joan Harbey, daughter of the Secretary to the Bank of England. Surprisingly there was only one romance. Miss Reddam, who spent most of working time in a bathroom, which we had some difficulty persuading the authorities to install. She married Dilly Knox [she was his secretary] and shared his somewhat bizarre office.64
