Room 40

A week-and-a-half ago, the world commemorated the one hundredth anniversary of the Battle of Jutland, the largest naval battle of the First World War. During the famous engagement, the British Grand Fleet sortied to intercept the main force of the German High Seas Fleet, which itself was trying to catch what they thought was an isolated portion of the Royal Navy.  The Germans were mystified when they were suddenly and unexpectedly confronted with a superior British force that seemed to know their exact location and course. At the time, they put it down to an unlucky coincidence. They could not have been more mistaken.

In fact, the Royal Navy knew exactly where the German fleet was and where it was headed because they had pulled off one of the greatest intelligence coups in military history. They had successfully broken the secret codes of the German Navy. This victory, bloodlessly achieved by brains rather than brute force, was one of the most important of the entire war.

Wireless telegraphy, what we today call radio, was still a new factor in warfare when the Battle of Jutland was fought. After all, it had been barely a decade since the experiments of Marconi proved the usefulness of long-range wireless transmitting. The advent of wireless technology made possible instant long-range communication, and with it, the coordination of military operations on a scale much larger than that ever achieved before. A commander was now able to give instant commands to armies or fleets hundreds or even thousands of miles away.

The problem with wireless is that anyone can listen in on it. It thus became necessary to deny the enemy knowledge of what was being said through the use of codes and ciphers. Failure to do this would allow the enemy to listen in on one’s own radio transmissions and could conceivably lead to disaster. Earlier in the war, the 1914 Russian invasion of East Prussia had resulted in a catastrophic defeat largely because the Russian commanders had communicated in the clear, without any attempt at using codes or ciphers, and the Germans therefore knew almost as much about Russian troop dispositions and movements as the Russians did themselves.

It was recognized quite quickly that wireless would be of particular use in naval warfare. While generals could communicate with their forces on land by cable or written message, admirals had to coordinate the activities of warships across vast stretches of ocean, and wireless was the only way to accomplish this. Before the war, in order to safeguard the security of its wireless transmissions from prying British eyes, the German Navy had carefully created a complex encryption system that consisted of three different codes.

Each code was known by a two-or-three letter codename. Perhaps the most important German code was SKM, which the Germans used only to communicate with important naval units during major operations. It was made up of more than 34,000 three-letter groupings, each of which represented an order, a name of a ship, or some other piece of information the German admirals would need to communicate to their vessels. A code of lesser importance was HVB, which the Germans used to issue various routine commands that were done on a regular basis, and also when warships needed to communicate with German merchant vessels. The final code, VB, was used by the German Admiralty to communicate with its naval attachés overseas, and also used by flag officers when they were at sea.

Wireless telegraphy was such a new innovation that few countries had put much thought into intercepting and decrypting enemy transmissions. When the war broke out, the British knew that the maintenance of their naval superiority was going to be a critical factor in the final defeat of Germany. If the Germans were able to seriously challenge British mastery of the seas, it would be impossible to maintain the naval blockade of Germany and the British Isles might find themselves threatened with invasion. Very early in the war, therefore, it was decided that an operation had to be set up to break the German naval codes.

The Royal Navy turned to a somewhat unlikely person to tackle this key problem: Sir Alfred Ewing, a Scottish engineer who taught at the University of Cambridge and had spent many of his pre-war years working in Japan. At the outbreak of the war, he was the Director of Education for the Royal Navy, helping develop better methods for recruitment and training of naval officers. He had absolutely no professional experience in cryptography, but Rear Admiral Henry Oliver, the Director of Naval Intelligence for the Royal Navy when the war broke out, simply had an intuitive feeling that Ewing was the man for the job. As it turned out, Ewing was an excellent choice.

As a first step, Ewing did what any intellectual would do when faced with such a challenge: he went to the British Museum and began reading books on cryptography. He also began to assemble a staff of quirky eccentrics to help him in his task. Since no one had ever assembled a team to break wireless codes before, Ewing essentially made things up as he went along. Among the men he recruited were mathematicians and linguists, but there was a heavy dose of intellectuals who were well-versed in classical languages and ancient history but had no knowledge of code breaking. Many of them were academics on leave from their universities, and there was a bit of culture shock as these civilians began working with officers of the Royal Navy.

The men recruited by Sir Ewing gathered in the quarters he had found for them in the Admiralty Building, Room 40, which was soon the unofficial name for the operation as a whole. The very existence of Room 40 was a highly-classified secret. Outside of the high councils of the Admiralty, only the top two British admirals, John Jellicoe and David Beatty, were allowed to know about it.

As it turned out, by the end of 1914, the men of Room 40 had a lot of material to work with.  Immediately upon the outbreak of the war, the Royal Navy and its Dominion counterparts had begun the straightforward task of ridding the world’s oceans of German merchant ships. Unless they were lucky enough to find refuge in a neutral port where they could sit out the war, any German steamship was soon to be captured by the British. All German merchant ships, of course, were under strict instructions to destroy their copies of the HVB code the moment it looked like capture was likely.

On August 11, a Royal Australian Navy ship boarded the German-Australian merchant vessel Hobart, whose captain was not even aware that war had broken out. The Australian officer commanding the boarding party presented himself as the head of a quarantine inspection unit, thus gaining control of the ship before the captain had a chance to destroy his codebook. The Australians then tricked the German into revealing the location of the codebook, which was soon on its way to London.

Only days later, Room 40 received another stroke out luck, courtesy of their Russian allies. In the Baltic Sea, the Germans and Russians fought a largely isolated naval war with one another, in which superior numbers and tactics gave the Germans a decided advantage. The Russians restored to the naval equivalent of a guerrilla war, launching occasional hit-and-run attacks, striking only when targets of opportunity presented themselves, and otherwise keeping their ships in well-fortified bases. 

During a sortie against the Russians in the first month of the war, the German light cruiser Magdeburg ran aground in heavy fog. Frantically, she tried to free herself before Russian warships could arrive and attack her in her vulnerable state. When it became clear that she was well and truly stuck, and that the Russians were indeed on their way, the captain of the Magdeburg decided to destroy the ship rather than see it captured. Being aground, it couldn’t be properly scuttled, but charges were set to blow the ship up. Two Russian cruisers soon approached and, as soon as they were in range, began firing at the helpless Magdeburg. In the confusion that reigned as the German crew abandoned ship, the charges apparently went off too soon, killing many of the German sailors while not fully destroying the ship. Some of the Germans were rescued by a nearby German destroyer, while the others were taken prisoner by the Russians.

When the firing died down, the Russians sent a boarding party onto the charred remnant of the Magdeburg. Onboard, they discovered the codebook and current key for the SKM code, and almost immediately recognized their significance. Figuring that the priceless codebook would be of much more use to the British than to themselves, the Russians made a copy of it and then generously sent the original to London, where it soon found its way to Room 40.

The final German code was said to have fallen into Allied hands through a bizarre coincidence. On November 30, in an incredible stroke of luck, a British fishing trawler accidentally hauled up a metal chest that had earlier been dumped into the North Sea by a damaged German destroyer. Upon investigation, it was found to contain the VB codebook. It’s not clear why a humble destroyer was carrying the VB codebook, which was used for communications to overseas naval attachés and consulates, or by Flag Officers, but the British certainly weren’t going to complain. (I have sometimes wondered if this story was cooked up by the British to conceal the fact that they acquired the VB codebook by stealing it from an overseas German embassy, which would have been a massive violation of diplomatic protocol and international law.)

Before the end of 1914, therefore, the British had acquired the three most critical German naval codes. Clearly, Room 40 led a charmed life. But simply having the codebooks did not allow the British to decrypt the German messages, because the Germans were using ciphers as well as codes. A code is basically just another language written down in a codebook, in which combinations of letters are substituted for regular words and numbers. A cipher, on the other hand, is a system of scrambling up those letters so that they appeared to be gibberish to anyone who doesn’t possess the cipher. The men in Room 40 may have obtained the German codes, but unless they could unlock the German ciphers, the messages they were intercepting still were incomprehensible.

The men at Room 40 set to work. There were no established methods and procedures for the work they were doing, so they simply starting building up their operation from scratch. They were helped by the fact that the Germans made excessive use of wireless and did not change their ciphers regularly. By assembling vast numbers of intercepted German messages and comparing them with one another, over time the ciphers began to be broken. By the end of 1914, Room 40 was beginning to read German messages with increasing ease.

One of the mysteries of the First World War is why the Germans never fully realized that their codes had been compromised and that the Royal Navy was, in effect, readings its mail. When the Magdeburg was captured, concerned messages fluttered around the German Admiralty regarding whether the vital SKM codebook had been successfully destroyed. No one could say for sure, but the Germans went right on using the code anyway. In all three of the German codes, ciphers were often not changed for weeks at a time, and as Room 40 gained in experience, each new cipher would be broken within a few days.

When the Royal Navy appeared as if from thin air to attack a German naval unit or intercept a German vessel, rather than consider the possibility that the British had broken the German codes, the German naval commanders ascribed these events to either unlucky coincidence or reports sent to Britain from spies in Germany. Indeed, in the entire German Navy, only Captain Looff of the Konigsberg, hiding in the Rufiji Delta in German East Africa, seems to have realized that the British could read the German codes. Supply ships clandestinely sent from Germany to assist the Konigsberg were intercepted by the British, who could only have known about them by breaking the German codes. But while Looff realized this, no one else in the German Navy seemed to comprehend it.

The first hint of what Room 40’s capabilities came during the Battle of Dogger Bank, when the Royal Navy was able to intercept a powerful German flotilla with an even more powerful flotilla of its own. Only good luck and poor British command and control during the battle allowed the Germans to escape a potential severe defeat. As it was, the Germans had been forced to flee for home with undue haste. The British victory at Dogger Bank was made possible only by the intelligence provided by the men in Room 40.

Eventually, the man who emerged as the guiding spirit of Room 40 and its devoted band of code-breakers was the new Chief of Naval Intelligence, Captain Reginald Hall, truly one of the unsung heroes of the First World War. He professionalized and reorganized the staff of Room 40, transforming the ad hoc group created by Sir Ewing into a proficient unit that not only provided critical intelligence for the British throughout the war, but laid the foundation of the future code-breaking operations at Bletchley Park during the Second World War.

In the middle of 1916, Sir Ewing took his leave from Room 40 and returned to academia, whereupon Hall officially took over Room 40 in his capacity as Director of Naval Intelligence. If the code-breaking operation had one weakness, it was organizational ambiguity, but Hall now cut through the red tape and greatly improved operations.

Room 40 would play a tremendously important role in the war. It would not only help the Royal Navy keep the German High Seas Fleet cooped up in its North Sea bases, but would help them defeat the U-boat threat that posed such a great danger to the survival of Britain. It would also help bring the United States into the war as a member of the Allied powers, for it was via the codebreakers in Room 40 that the notorious Zimmerman Telegram came to be revealed to the public, raising American anger against Germany to a fever pitch in the early months of 1917.

If ever there was proof that the simple power of the human mind, carefully applied, can change the course of history, it was in the work of the men in Room 40.