Every day, the watchkeepers in Room 40 received hundreds of coded and enciphered German messages that had been intercepted by an array of wireless stations erected on the British coast, and then sent to the Old Building by land telegraph. Germany had been forced to rely almost exclusively on wireless communication after Britain, in the first days of the war, had followed through on its 1912 plan to cut Germany’s undersea cables. The intercepted messages arrived in the basement of the Admiralty building and were then relayed to Room 40.
It was the task of Room 40 to translate these messages into the King’s English, a process made possible by a series of nearly miraculous events that occurred in the closing months of 1914 and put the Admiralty in possession of three codebooks governing German naval and diplomatic communications. By far the most important, and secret, was the German navy’s SKM code, short for Signalbuch der Kaiserlichen Marine. In August 1914, a German destroyer, the Magdeburg, ran aground and was cornered by Russian ships. Exactly what happened next remains unclear, but one story holds that the Russians found a copy of the codebook still clutched in the arms of a dead German signalman whose body had washed ashore after the attack. If so, it was probably the codebook that killed him: it was large and heavy, 15 inches by 12 inches by 6 inches, and contained 34,304 three-letter groups used to encode messages. The letters MUD, for example, stood for Nantucket; Liverpool was FCJ. The Russians in fact recovered three copies of the codebook, presumably not from the same body, and in October 1914 gave one to the Admiralty.
The codebooks were invaluable but did not by themselves reveal the contents of the intercepted messages. Their German authors used the volumes to obscure the original plain-text messages but then subjected the encoded versions to a further scrambling through the use of a cipher. Only holders of a cipher “key” could divine the underlying text, but possessing the codebooks made the whole process of solving the messages far simpler.
To exploit these treasures the Admiralty established Room 40. In a handwritten directive, Churchill set out its primary mission, “to penetrate the German mind,” or, as one of the group’s key officers put it, “to extract the juice.” From the start, Churchill and Fisher resolved to keep the operation so secret that only they and a few other Admiralty officials would ever know it existed.
Equally mysterious—though unintentionally so—was the matter of who actually managed the group. On paper, at least, it reported to Adm. Henry Francis Oliver, the Admiralty’s chief of staff, a man so tight-lipped and reticent he could seem almost mute, and this—given the British navy’s predilection for nicknames—ensured that he would be known forever after as “Dummy” Oliver.
Within Room 40 itself, however, management of day-to-day operations fell largely, if informally, to Cdr. Herbert Hope, recruited in November 1914 to bring naval expertise to the interpretation of intercepted messages. His savvy was badly needed, for the group’s staff were not navy officers but civilians recruited for their skill at mathematics and German and whatever else it was that made a man good at breaking codes and ciphers. The roster came to include a pianist, a furniture expert, a parson from northern Ireland, a wealthy London financier, a past member of the Scottish Olympic hockey team, and a dapper operative named C. Somers Cocks, who, according to one early member, William F. Clarke, was “chiefly remarkable for his spats.” The unit’s women—known as “the fair ladies in forty”—served in clerical roles and included one Lady Hambro, wife of a prominent financier, who according to Clarke startled everyone at one of the group’s annual dinners by smoking a large cigar. Wrote Clarke, “It was the best of jobs and we were a happy band in those days with the best possible of chiefs in the person of Hope.” Hope was modest and retiring, and a skilled manager, Clarke recalled, and “all of us became deeply attached to him.”
Hope’s authority was recognized outside Room 40 as well, much to the displeasure of Dummy Oliver, who was said to be obsessed with controlling who saw the deciphered intercepts and what was done with the information they revealed. When First Sea Lord Fisher made his initial visit to Room 40 and saw firsthand what the group was doing, he ordered Hope to bring him the latest intercepts in person, twice a day.