Course Handout - Codes and Ciphers in History, Part 2 - 1853 to 1917

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First published online 09:49 GMT 27th January 2003, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 18:00 14th January 2010


Although this paper is reasonably self-contained, it is best read as the middle part of a three-part subordinate file to our six-part review of how successfully the psychological study of biological short-term memory (STM) has incorporated the full range of concepts and metaphors available to it from the computing industry. To go directly to the superordinate content file, click here, to go to the superordinate menu file, click here, and to see the author's homepage, click here.


Cryptology and the Electric Telegraph (1853-1865)

"Without communications, I command nothing but my desk." (General Thomas Power, USAF, cited in Woods, 1974.)

The story of the development of the electric telegraph was told in detail in Part 1 of the main paper, and the "Great Game/Tournament of Shadows" was introduced towards the end of Part 1 of this historical review. These apparently unconnected threads of history came together in the Crimean War (1853/4-1856). The immediate cause of this war was the Russian annexation of the Crimean Peninsular from the Turkish Empire. They did this as an attacking move in the Tournament of Shadows, calculating that it would give them a greater Black Sea presence, and thus greater influence throughout the Mediterranean and the Middle East. To help counter this, Britain (under Queen Victoria) and France (under Napoleon III) suddenly had cause to forget old differences and become allies. The Russian-Turkish war began in October 1853, when Tsar Nicholas I seized upon a (possibly engineered) atrocity in Bethlehem to seize Turkish possessions on the Lower Danube. Britain and France then declared on the Turkish side on 28th March 1854, although little actually happened until September that year, because that was how long it took for a joint British-French expeditionary force to arrive in the Crimea. The expeditionary force established a bridgehead at the port of Balaclava, and the campaigns which followed became the first major war to be fought in the age of the electric telegraph, and gave the new technology a thorough baptism of fire.

The Crimean telegraph had two distinct aspects, namely (a) an eight-station theatre telegraph system around Balaclava, and (b) a submarine cable link to Varna, 340 miles away across the Black Sea (on the coast of what is today Bulgaria). The theatre system was laid by a cable-laying party under Lieutenant Stopford of the Royal Engineers, and was ready for service after only a few weeks [one of the two cable wagons used, and other equipment from this period, is on display in the Royal Signals Museum, Blandford, Dorset]. The submarine cable followed in April 1855, and, for the first time in the history of warfare, put field commanders in direct and nearly immediate touch with their respective war departments. However, not everybody responded equally to the new technology. For the French, Napoleon III kept personal close contact with the commander of the French forces, but for the British the new technology became - it seems - an avenue for petty bureaucrats to raise minor administrative problems. Perhaps not surprisingly, therefore, another textbook example of poor military communication - the Charge of the Light Brigade - comes from this very war.

For their part, the Russians took out a spur from their Siemens and Halske telegraph system in Odessa, and ran it all the way to Sevastopol (where according to Woods, 1974, they got it operational just in time to inform Moscow that the city was about to surrender). The Vigenère polyalphabetic cipher was one of the main codes used by the Russians, and it has been suggested that this is why such an unearthly silence greeted the British computing pioneer, Charles Babbage, when he managed to crack it in 1854.

ASIDE: Both Singh (1999) and Swade (2000) tell the story that in 1854 a Bristol dentist named John Thwaites published claims to have invented a new cipher system. Babbage responded that the man had actually re-invented the as-yet-uncracked Vigenère cipher. Disappointed, the man challenged Babbage to crack it anyway, and he did, by analysing the ciphertext for patterns of a higher order than simple letter frequencies (Singh explains that the principle of counting letter groupings rather than the letters individually will result in repeats of common words - eg. BUK for "the" - if coincidentally they are a multiple of the key length apart in the plaintext). What Babbage could not do, however, was publicly proclaim his breakthrough, for then the Russians would immediately stop using the Vigenère. There would be plenty of opportunity for Babbage's decryption method to be tested, but only as long as he kept his discovery to himself. The 1854 break did not become public knowledge, therefore, and the credit is nowadays given to the Prussian Friedrich Kasiski, who arrived at the same method in 1863. Singh gives a detailed worked example, if interested. 

Three thousand miles to the east, the local rebellions continued in British India. The telegraph here had to cope with distances on a truly continental scale. A telegraph line opened between Agra and Calcutta (800 miles) on 24th March 1854, and by 1856 had been extended to Bombay, Peshawa, and Madras. The engineer in charge was William (later Sir William) O'Shaughnessy, of the East India Company, who had successfully demonstrated an experimental 13-mile of telegraph near Calcutta as early as 1839 (John H. Lienhard, 2002 online, on the excellent "Engines of our Ingenuity" website, University of Houston). Telegraph development was then forcefully promoted by Lord Dalhousie, after he became Governor General of India in 1847, and O'Shaughnessy's system was fully operational in 1851. Amin (1999/2002 online) explains how the introduction of western postal and telegraph services in the sub-continent gave the Indians a new sense of their own political identity, thereby elevating humble cable and keys to being one of the causes of the Indian Mutiny (1857-1859). The rebellious Sepoys certainly fully appreciated the telegraph's tactical significance, and regularly targeted telegraph offices and the lines themselves. This in turn prompted acts of bravery such as that of the 18-year old Delhi telegraph operator George Brendish, who, with his officer killed, remained at his equipment keying warnings until the last possible moment [picture; example]. Woods (1974) dates the first Indian field telegraph (that is to say, the deployment of equipment mobile enough to stay close to the action and deliver real time tactical support) to 1858, when a wiring party accompanied the British relief column on its way up to Lucknow.

The 1850s were also a formative period for American military signalling. The leading figure here seems to be Major Albert James Myer (1829-1880), who turned his early experience as a physician teaching sign language to the deaf to military purposes, introducing a hand-held semaphore signalling system (colloquially, a "wig-wag" system) into the US Army in 1856. Myer's system was so well received, that in June 1860 he was transferred from the medical corps to the newly established US Army Signals Corps, and his system was then put to the acid test by the American Civil War (1861-1865).

The American Civil War was fought over territory which already had a large pre-existing telegraph network. Both sides therefore arranged for their field telegraph systems to bridge into that existing network, and the northern states - the Union - even set up the War Department Telegraph Office to coordinate the fixed and the battlefield networks. In August 1861, Myer proposed attaching a telegraph signal unit to every army on the march, and thanks to the foresight of Colonel Thomas A. Scott, Assistant Secretary of War, this was duly authorised (Woods, 1974). It was then necessary to keep all the additional telegraph traffic secret, and Anson Stager, of the Western Union Company, was recommended for the job. Stager duly set about designing and administering the ciphers to be used, and did the job so assiduously that the southern states - the Confederacy - never managed to crack them (Kelley, 1999 online). President Lincoln is reported to have spent considerable time in Stager's cipher office in Washington, deeply intrigued by what went on in nineteenth century cyberspace (Greely, 2002 online). The telegraph service made no military decisions on its own, of course; it merely fed information up into a sometimes inconsistent military intelligence superstructure (Finnegan, 1994/2002 online). The Union also made use of the pre-war detective agency run by the Scottish emigré (and one-time workers' rights activist), Allan Pinkerton, although Finnegan dismisses Pinkerton's contribution as "mostly misinformation" (op. cit.).

As a basically rural economy, the Confederacy had less access to state-of-the-art hardware than did their enemy. However, they compounded this shortcoming with another; that of failing to create a central co-ordinating department like Stager's. Instead, they were content to leave individual commanders to select their own encryption methods. The Vigenère polyalphabetic system was frequently used, and reasonably secure, but the schoolboy Caesar shift was not unknown, as was no protection at all. On balance, therefore, Ryan and Ryan (2002 online) conclude that Union commanders enjoyed significant access to what the Confederates hoped and believed were secret communications: "The South's failure to protect critical information," they argue, "undoubtedly contributed to many Yankee victories".

The Ryans point especially to the Battle of Antietam on 16th-18th September 1862 as the "most catastrophic" (and in the end pivotal) example of Confederate cryptological negligence. This was a supremely violent battle in which the Union General George B. McClellan had to blunt a multi-column advance by Confederate General Robert E. Lee, and by the time it was all over there had been twice as many casualties as in the 1812, Mexican, and Spanish-American Wars put together, and four times as many as were suffered during the D-Day landings 82 years later. The intercept on this occasion was very low tech - nothing more complex than the loss from an unknown Confederate staff officer's pocket of an en clair copy of General Lee's special order #191 for the invasion of Maryland.

ASIDE: The Confederates were in fact thrice negligent at Antietam, (a) for not enciphering the order in the first place, (b) for simply losing it, and (c) for not monitoring their enemy's newspapers (specifically, for failing to abort their attack after the New York Herald had stupidly reported the intercept on 15th September); in fact, Robert E. Lee subsequently claimed that he only learned of the loss early the following year (Fishel, 1996).

Nor was Antietam the Confederacy's only error. Their agent Rose Greenhow made the elementary mistakes (a) of keeping copies of her reports, and (b) of keeping at least one set of matching plaintext and ciphertext. When she was arrested by the Pinkerton agency on 23rd August 1861, the forensic cryptanalysis was simplicity itself (Horan, 1970). The lesson here (yet again) is that it takes more than an encryption system to make a successful encryption service: Mrs Greenhow was an enthusiastic amateur who broke commonsense procedural rules, and we will shortly be seeing how similar gross procedural errors would compromise the German encryption systems in World War Two (see Part 3).

Civil War telegraph technology also had tactical implications. The inventor George W. Beardslee patented a battery-free telegraph system in 1857 to capitalise on the need for a lighter, and therefore field-portable, telegraph station. These units were first adopted in May 1862, and 30 of them were in use by 1863 (Woods, 1974). The following extract will give a flavour of what was possible once it was no longer necessary to drag a heavy battery wagon along with you:

"The army signal-telegraph has been so far perfected that in a few hours quite a large force can be in constant connection with headquarters. This while the battle is progressing, is a great convenience. The wire used is a copper one, insulated, raised on light poles made expressly for the purpose, on convenient tree, or trailed along fences. The wire and the instrument can be easily carried in a cart, which as it proceeds unwinds the wire, and, when a connection is made, becomes the telegraph office. Where the cart cannot go, the men carry the drum of wire by hand. [] The machine is a simple one, worked by a handle, which is passed around a dial-plate marked with numerals and the alphabet. By stopping at the necessary letters, a message is easily spelled out upon the instrument at the other end of the line, which repeats by a pointer every move on the dial-plate. (Harper's Weekly, 24th January 1863; from the website of the Ohio Valley Civil War Association.)

Thus whereas Stopford had ploughed his wires two feet down into the Crimea in 1855, less than ten years later we have the signallers in much closer tactical support to the front line. Needless to say, these field telegraph systems immediately became prime targets in themselves, and when you were not wiretapping, you were wire cutting [see, for example, Abruscato and Hara, 1999-2001 online]. Both sides took to sending out small groups of telegraph technicians accompanied by skilled backwoodsmen, to cut into the enemy's wires in some secluded spot. One of the most striking examples of this was C.A. Gaston, General Robert E. Lee's personal telegraph operator, who tapped General Grant's network during the siege of Richmond, VA, for no less than six weeks (Greely, 2002 online). [For the fuller story, see W.R. Plum's "History of the Military Telegraph in the Civil War" (1882/2000 available in facsimile). Fishel (1996, p4) plays down the importance of tappings, reporting "only one brief tap" (presumably Gaston's).]


Spies on the Line (1866-1902)

The "Confederation of the Rhine" was established in 1806 as Napoleon's way of making some sense of the ruins of the Holy Roman Empire, whilst keeping Germany divided and weak, and France strong. However, from the German point of view not enough of these provisions were reversed in the 1815 Treaty of Vienna. This was because Habsburg Austria still held too many of the cards. The most influential Austrian at the treaty negotiations was Prince Klemens von Metternich (1773-1859), and the resulting German constitution left the German-speaking people as a collection of 39 separate states, with the Austrians having the most votes. This led during the 1820s and 1830s to social unrest in many of these states, and, before long, to a reaction against the overbearing Austrian-ness of Metternich's Vienna.

The German unification movement flourished in the 1840s , championed by the largest of Austria's rivals, Prussia, which saw itself as the ideological and ethnic heartland of a larger German empire, and in May 1848 the "Frankfurt Assembly" was convened with a brief to draft a suitable constitution for a unified northern Germany and to appoint its first emperor. Somewhat optimistically, given the extent of the opposition from the Habsburg establishment and Tsarist Russia, the assembly invited King Friedrich Wilhelm IV of Prussia to become the first imperial Kaiser, but he did not feel sufficiently certain of himself to accept. It took another twenty years for the German nationalists to recover from this setback, but recover they did, and the central figure in the renewed manoeuvring was by now Otto von Bismarck (1815-1898). Bismarck became Prussia's Minister-President in 1862, and immediately embarked on a national muscle-building programme, during which the Prussian army was progressively developed. They were tested in 1864 when the lands of Schleswig and Holstein were taken from Denmark after a pretty one-sided six month campaign.

Now we mention all this, because in 1866 Prussian eyes turned to the Habsburg territories of Silesia and Bohemia, and to help it in this deliberately engineered confrontation a counterintelligence organisation named the Abwehr was established. Abwehr agents were placed in key positions throughout the capitals of Europe, and those in Vienna were combat tested almost immediately in the Austro-Prussian War (1866) (the "Seven Weeks War"). This time it was the Habsburg's turn to be humiliated, for the Prussians ripped apart the Austrian army at the Battle of Königgrätz on 3rd July 1866, and by the Treaty of Prague on 23rd August the German states were reconstituted as the Prussian-led "North German Federation".

ASIDE: Though not much spoken about nowadays, Königgrätz was at the time the largest battle ever fought in Europe, involving more than half a million men. It is historically significant not just for heralding the end for the Habsburg dynasty, but also for proving the success of the latest German military tactics.

With Germany unified and Austria sidelined, Bismarck's gaze now turned to Alsace-Lorraine, on the west bank of the Rhine. This automatically placed them at odds with France, but they were lucky because the French were in an over-confident and slightly decadent national mood, lulled by the success of their 1867 Great Exhibition (Horne, 1965, sees a larger truth in the fact that the French exhibited "the beautiful and the frivolous", whilst the Prussians were showcasing the latest Krupp armaments).

So successfully had the Abwehr done its job in 1866, that it was recommitted in strengthened form in the Franco-Prussian War (1870-1871), after Napoleon III had been goaded into declaring war on Germany. One of its most thoroughly documented agents was August Schluga. Schluga - codenamed "Agent 17" - was active from the very beginning of the service and reported on the situation in Paris in 1870 to the German military attaché there, Lieutenant-Colonel (later Field Marshall) Alfred von Waldersee. He remained in business until forced by ill health into retirement in 1917 (Pöhlmann, 1999/2002 online), but one of his ciphertexts is on the web, if you fancy the challenge [view]. Brückner (1998/2002 online) remains unimpressed with Schluga's overall contribution, describing it as merely "interesting". Wilhelm 1 was proclaimed Kaiser on 18th January 1871, and Bismarck promoted to Reichskanzler of the German Empire - the "Second Reich" (the "First Reich" was deemed to have been the Holy Roman Empire) - a position he held until retiring in 1890.

One analysis of the turbulent 1860s and 1870s has since become became a classic of cryptanalytical theory, Auguste Kerckhoffs' "La Cryptographie Militaire" (1883). Kahn discusses Kerckhoffs' work in some detail (Chapter 8), and draws particular attention to his insight that different rules applied to the occasional communications of ambassadors and gentlemen than did to heavily used battlefield communication systems. In fact, there were two fundamental requirements for a successful field cipher system, namely (a) that it could cope with the volume of traffic likely to be thrown at it, and (b) that its inventors/manufacturers were not necessarily the best people to appraise their systems' weaknesses - thieves needed to be set to catch thieves.

The last quarter of the nineteenth century saw a lot more imperial wars, and the Great Game in particular was far from over. Rainwater (2002 online) describes how a new "forward policy" was brought into British imperial strategy when Benjamin Disraeli became Prime Minister in 1874. By now, the Russians were making major inroads into the Turkish Empire, and had established their influence across Central Asia, Britain needed to defend the northern borders of the Indian subcontinent. This resulted in the Second Afghan War (1878-1881), during which they were tormented by a force of agents provocateur reporting to Moscow.

ASIDE: When Alexander II was killed by an anarchist bomb in 1881, his son, Nicholas II, actually supplemented his international intelligence service by forming the Special Department, the Okhrana, who served him much as the Gestapo would later serve Adolf Hitler, and who were, for a time probably the most effective SIGINT organisation in the world (Casey, 2002 online).

The nineteenth century closed with two further telegraph-assisted wars. The Spanish-American War (1898) saw the Americans deliberately targeting their intelligence operatives on the Western Union telegraph office in Havana, so as to monitor communications between local commanders and their commanders-in-chief in Madrid, and the Anglo-Boer War of 1899-1902 saw the British relying on the established Wheatstone Automatic telegraph. Some 18,000 miles of cable were laid during this war (Royal Signals Museum website), and despite constantly having to cope with cut wires successfully delivered 13,500,000 messages. Not that all of these arrived intacta at their destination: Philip Pienaar, one Boer telegraphist, once got "the entire plan of campaign for the next four weeks" by tapping General Hamilton's telegraph line (Pienaar, 1902, cited in Lee, 1985). The archives at King's College London include two volumes of cipher telegrams between the Secretary of State for War and General Sir Horatio Herbert Kitchener, Commander-in-Chief, South Africa. The British also experimented with sending their messages in arcane languages such as Hindustani (Deacon, 1980), a ploy repeated by the Navajo "windtalkers" in World War Two, and popularised by the 2002 movie of the same name.


Spies on the Air (1897-1917)

Note: Although the words "wireless" and "radio" both mean much the same thing nowadays, they derive from different inventors. For the sake of convenience, we shall use the former as short for "wireless telegraphy", that is to say, station-to-station aerial telecommunication using Morse or other non-voice codes, and the latter as short either (a) for "radio telephony", station-to-station aerial telecommunication of the spoken voice, or (b) "radio broadcasting", the undirected transmission of the spoken voice to a large and individually anonymous audience.

Following only three years of basic experimentation, Marconi's Wireless Telegraph and Signal Company (see Part 1) started successfully demonstrating its wares in August 1897. Orders were immediately forthcoming from the world's navies, merchant marines, and news agencies (all those, in fact, who had been most restricted by the hard-wired world of telegraphy). Things then moved very quickly indeed. For example, the Prince of Wales was able to dictate a message from on board the Royal Yacht on 10th August 1898, and a year later messages from the wireless room aboard HMS Defiant managed to control a fleet of three ships at sea. The first theatre trialling of wireless telegraphy was by the British in 1899, during the Boer War [picture], although no substantive content was carried. A Boer order for six wireless sets from Marconi's German rivals Siemens and Halske, was impounded as contraband upon arrival at Capetown (IEEE website). The experiment was repeated in Somaliland in 1903 by Lieutenant Arthur E. Silvertop, RN, but poor earthing and adverse atmospherics restricted the effective range to only 33 miles (Trappes-Lomax, 1955), and over the ensuing decade, much important research was carried out by Henry J. Round (1881-1966), of the Marconi Company. Maurice Wright, a Marconi technician, worked with Round on a high-power wireless receiver, and was intercepting German wireless traffic from the company's Chelmsford laboratories two days before the outbreak of the war.

The new technology immediately prompted renewed interest in the science of encryption, for whenever you sat down at your transmitter you were deliberately risking your secrets "on the air" - anybody who could get their hands on a suitably tuned receiving set could listen in, and that included your enemies. Indeed, one of the very first messages to pass from England to France, on 29th March 1899, was sent in a simple cipher, not because it was secret but because its originators wished to ensure thereby that the equipment was not an elaborate hoax of some sort (McClure's Magazine, June 1899). Cryptology was accordingly a major aspect of First World War military intelligence, and the French, building on the traditions of Vigenère, Rossignol, and Kerckhoffs, were again reputedly the best at it (Kahn, 1996). They broke the German double transposition system in October 1914, and one of their best cryptanalysts, George Painvin, was single-handedly responsible for blunting a major German offensive in 1918. For their part, the Germans annihilated an entire Russian army at the Battle of Tannenburg in August 1914, because the Russians, having botched the distribution of their codebooks, resorted to using unencrypted radio transmissions (Finnegan, 1994).

The British efforts were concentrated in Room 40 at the Admiralty, a department which was founded by Sir Henry Oliver in 1914 and headed by Captain (later Admiral) William Reginald ("Blinker") Hall (1870-1943). Their operations were helped by the capture in 1914 of codebooks from two sunken German vessels, and in 1915 of a copy of the diplomatic codes. They were also impressed by Round's August 1914 eavesdropping success, and directed Marconi to release both Round and Wright for special duties developing a network of wireless tracking stations around Britain (Wright, 1987). These were codenamed the "Procedure 'Y' Stations". Wright even ran an illicit listening station in neutral Oslo for six months in 1915, escaping capture only by a whisker.

ASIDE: ASIDE: The Y-Stations were used extensively in both world wars, and provided the Bletchley Park codebreakers (see Part 3) with much of their raw material. Maurice's son, Peter, himself had an eventful career in British counterintelligence, claiming to have identified the "fifth man" in the Burgess-Maclean-Philby-Blunt spy scandal of the 1950s-1970s, and publishing the best-selling "Spycatcher" in the late 1980s (Wright, 1987).

The war at sea was also a learning experience for all involved. The naval battles of Coronel (1st November 1914; two British warships sunk by a five-unit German cruiser squadron under Admiral von Spee) and the Falkland Islands (8th December 1914; Royal Navy revenge) highlighted the need for new tactics and strategies. Wireless intercepts from ports along the eastern and western coasts of South America guided the opposing fleets (often by tracking their supply ships to their secret rendezvous). Only the Dresden escaped the Royal Navy at the Falkland Islands, and the next three months were spent playing hide and seek from Valparaiso to Cape Horn. She was finally located by radio intercept in early March 1915, which, when deciphered by the Room 40 people, gave the position of a planned rendezvous 300 miles out into the Pacific from the Chilean mainland. A final wireless-aided chase ensued, resulting in the Dresden being run to earth at nearby Mas a Fuera, where she was scuttled after a short fire-fight. The Germans got their own back a year later, when on 26th May 1916 the Abwehr's marine section managed to decipher an out-of-the-ordinary mine-clearance report. This intercept enabled them to re-seed the cleared channel within hours, and the next ship out through it was HMS Hampshire, carrying the British Commander-in-Chief, Lord Kitchener, on a visit to Russia. It struck one of the newly laid mines, and was lost with nigh on all hands.

ASIDE: One of Dresden's officers, a young Lieutenant named Wilhelm Canaris, managed to escape Chilean internment, and made his way back to Germany. By 1932, he had risen to the rank of Captain, and at Christmas 1934 was put in charge of the Abwehr. Remembering the Dresden and the Hampshire, he never forgot the strengths and weaknesses of wireless. Indeed, he even authorised his own Enigma network, which the British Bletchley Park codebreakers (see Part 3) had to form a separate team to monitor. 

The Americans, too, were learning new skills the hard way. In 1914, Ralph van Demen created a Military Intelligence Cipher Bureau under Herbert O. Yardley (1889-1958), poker player turned cryptanalyst. The new service saw action between March 1916 and February 1917, when General John J. Pershing mounted a punitive expedition against Mexico's Pancho Villa for armed incursions into New Mexico [details]. Not only was this the first opportunity for the Americans to use aircraft and motor vehicles in action, but it also allowed them to make full use of the latest telecommunications technology. Unfortunately, Pershing was searching for a force of Mexican irregulars in a land which largely adored them. The Villistas were therefore able to appear and disappear at will, and when they fought at all it was as guerrillas. Pershing countered this by appointing Major James A. Ryan as his intelligence officer, and the latter set about organising a network of telegraph and telephone listening stations (Rafalko, 2002; Chap3 online). The Signal Corps also provided the "radio tractors" which did the monitoring (Finnegan, 1994), although it must be presumed that these heard more from the legitimate Mexican government than from Pancho Villa's ill-equipped irregulars. Many of the intercepted messages were passed in the first instance to Captain Parker Hitt of the Signal School at Fort Leavenworth, KS. Captain Hitt was the US Army's resident expert on cryptological techniques, and had already put together the service book on the subject in 1915. Pershing's official report included the following:

"It was early observed that the Mexican authorities had no code in general use but that each commander had his own local code []. This department took up the study of code messages and soon was able to decipher any code used in Northern Mexico. Thereafter, by tapping the various telegraph and telephone wires and picking up wireless messages we were able to get practically all the information passing between the various leaders in Mexico." (Pershing's "Report of the Punitive Expedition", quoted in Finlay, 1993.)

The Pershing expedition was finally recalled in January 1917, by which time relations with Mexico's official government were at a new low (a fact which - as we are about to see - was far from lost on the Germans). Much had been learned, however, and the experiences of a young Lieutenant named George S. Patton would prove particularly valuable a quarter of a century later when, as one of Eisenhower's Generals, he combined duties preparing the (real) US Third Army for the Autumn 1944 drive across France with inventing the radio traffic for a totally fictitious First Army Group (Tavares, 2001). Other members of either the expeditionary or the border defence forces who later became famous were Omar N. Bradley, Matthew B. Ridgway, and George C. Marshall, the only professional soldier ever to have been awarded the Nobel Peace Prize (in 1953) (Finlay, 1993).

Room 40's highest profile success was to ensure the entry of the US into the war in the spring of 1917. This story begins with a telegram transmitted on 16th January 1917 from the German Foreign Minister, Arthur Zimmermann, to Count Johann von Bernstorff, his Ambassador in Washington, warning them that the Kaiser's Supreme Command had just decided as a point of grand strategy to intensify the U-Boat campaign in the Western Atlantic. This broke previous German undertakings to the US, and risked bringing the US into the war on the side of France, Britain, and Russia. Von Bernstorff was accordingly instructed to try to persuade the Mexicans to attack the US from the south. What Zimmermann did not know was that the trans-Atlantic telegraph cable was being routinely tapped by a British black chamber [yes, they were still around; and yes, they still are], and so the "Zimmermann intercept" was soon in Room 40. The problem then was that its high diplomatic priority meant that it was in a relatively new cryptographic system known as 0075, which Room 40 had yet to master, despite six months of trying. Nevertheless, enough words could be made out to give some hint as to the message's importance, so it received priority attention.

Now Hall knew that the second leg of the transmission, from Washington onwards to the German Legation in Mexico City, would probably travel by an older encryption system known as 13040, which Room 40 could decipher. He therefore placed an operative, codename "T" (Kahn, 1996), in the telegraph office in Mexico City, and a few days later Room 40 knew the German plan in full.

The British were immediately faced with the classic codebreaker's dilemma, namely whether to respond to a decryption, and thus reveal the true extent of their cryptanalytical competence, or keep quiet and suffer the consequences.

ASIDE: Having broken a code, it becomes important not to reveal that fact too directly. Specifically, you cannot afford to be "right too often", or your enemy will smell a rat, improve his systems, and you will be back where you started. There are two ways around this difficulty. One is to rely on (sometimes very elaborate) subterfuges, in which totally fictitious spies are praised for having obtained the information in question through more conventional espionage methods (Bury, online). The other is just to play dumb; to pretend you have not received this or that warning, sit back, and just let things happen. Needless to say, this means that the people in the hot seats end up having to play God with the lives of the people on the receiving end of whatever happens to be afoot. Military intelligence is accordingly a world of harsh realities and seamy secrets, when enemy intentions are known, but no action is taken to respond to them. Nor do things get any better: one very compelling (but entirely speculative) explanation of the failure to prevent the Omagh terrorist bomb in Northern Ireland in August 1998 is that after a string of successful "busts" the security forces had determined to let a bomb go through "undetected" to preserve the integrity of their informant. They therefore responded deliberately slowly to telephoned warnings, and 29 innocent bystanders were killed.

Hall decided to do nothing hasty for a day or two, but when the torpedoing did start again, it soon became apparent that President Wilson was still vacillating. In mid-February, therefore, with British shipping losses starting to mount, Hall finally took matters into his own hands, and revealed his decrypt to his superiors, and together they hatched a scheme to have the Americans learn "for themselves" of the German grand strategy. Using diplomatic contacts at the US Embassy in London, they passed the Americans the transcript of the Mexico City version of the telegram, which, since it matched a ciphertext the Americans themselves already had on record, could then be treated as both discovered and decoded on American soil. President Wilson duly made the matter public, and the story hit the streets in the morning papers on 1st March 1916, causing such a violent swing of public opinion against the Kaiser that the US declared war on Germany just over a month later.

Here are the first few lines of the Zimmermann telegram, as intercepted, to give some feeling for a large numeric codebook. For the full ciphertext, click here, and for the decrypts, click here and here.





















































See Main Menu File.


Where Next


[Codes and Ciphers in History, Part 1 - to 1852]

[Codes and Ciphers in History, Part 3 - 1918 to 1945]

 Recommended Reading

"The Code Book: The Secret History of Codes and Code-Breaking"

Singh, S. (1999)

To see an abstract, or to order this book, click here

[Singh's Code Book jacket]


Recommended Reading

"The Zimmermann Telegram"

Barbara Tuchman (2001)

To see an abstract, or to order this book, click here

[Tuchman's Zimmermann Telegram jacket]