Kitabı oku: «Blood, Tears and Folly: An Objective Look at World War II», sayfa 5
The changing map of Europe
At the start of the war the only fully updated operational maps in Whitehall were to be found in the Admiralty’s Upper War Room. This 300-year-old library had been made into a map room which was manned round the clock. The maps were coloured in pastel shades (because Churchill said primary colours gave him headaches) and pins showed the position of every British and Allied warship and convoy as well as the position of every German vessel reported by intelligence. The U-boat war, complete with a day-by-day account of shipping sunk and the import figures, was the room’s most important concern.
The map room became a regular treat for guests after Churchill’s Tuesday evening dinner parties. He was first lord of the Admiralty11 at this time, slept nearby, and would appear suddenly in his multicoloured dressing-gown inquiring about the latest news. Last thing at night and first in the morning he was briefed. When in May 1940 he became prime minister he no longer had this map room close at hand but the same officers provided a similar early morning briefing to him throughout the war.
In September 1939 Germany went to war with only minimal need for ocean trading. Agriculture, which the Nazis had encouraged, supplied enough food; and German mines enough coal and iron-ore. When and if some special top-grade ores were needed by the armaments industry Sweden was very close and willing to sell. Other imports came from Switzerland and Italy. Rubber and oil were the most vital necessities but German scientists were already able to provide adequate synthetic versions of both, and the Romanian oilfields were on the doorstep. Furthermore Germany had a new friend and trading partner – the USSR – which had oil to spare. Poland had been invaded by both countries, split down the middle and shared between them. Direct cross-border trade began. The Germans could now reach the whole of Asia without worrying about the Royal Navy’s blockade.
All this was evident from a map, but there was little sign that many members of the British government looked at a map. In March 1940 Prime Minister Chamberlain was calling blockade ‘the main weapon’. Britain’s Ministry of Economic Warfare said, and believed, that the German economy was on the point of breakdown. On 27 May 1940 Britain’s chiefs of staff predicted that Germany’s economic collapse would take place by the end of 1941. By September 1940 – with Hitler controlling Europe from Norway to the Spanish border, and the Battle of Britain still undecided – the chiefs of staff had not changed their mind. The prevailing opinion was that Germany’s inevitable collapse would now be speeded by the rebellious people of the occupied countries. The role of the British army in 1942, they cheerfully predicted, would merely be to keep order in that chaotic Europe left by the German disintegration! We must not be too hard on those wishful thinkers: such fantasies kept Britain and her Dominions fighting in a situation that more realistic minds would have pronounced hopeless.
The division of Poland, between Germany and the Soviet Union, and the trade between them was not the only bad news that the admirals had to swallow in that 1940 summer. The Admiralty had always assumed that in the event of war it would enjoy port facilities in Ireland. From fuelling bases at Queenstown (Cobh) and Berehaven and the naval base at Lough Swilly on the west coast, anti-submarine flotillas would have ranged far out into the Atlantic. Without them every escort vessel would add 400 miles to its patrol. The use of the bases in wartime had been confirmed in a conversation between the Irish patriot Michael Collins, Admiral Beatty and Winston Churchill as long ago as 1922, when Churchill, as colonial and dominions secretary, was concerned with the Irish Settlement.
The story behind this change has still to be told to everyone’s satisfaction. In April 1938 the Chamberlain government renounced the right to use the ports which it had been granted under the 1922 Irish treaty. Churchill was appalled and said that it would be hard to imagine a more feckless act at such a time. In the House of Commons he spoke against what he called a ‘gratuitous surrender’ and a ‘lamentable and amazing episode’. He found himself unsupported. Virtually the whole Conservative party, and the Labour (Socialist) and Liberal opposition, sided with Chamberlain. But when war came, the Irish Republic remained neutral and Churchill’s warnings proved exactly true. Ireland’s government resisted Britain’s requests to use the ports, although some of the material brought in the convoys was destined for neutral Ireland.
The convoys, channelled into the narrow waters around Ireland, provided rich pickings near home for bold U-boat captains. The Admiralty was still coming to terms with these difficulties when, in the summer of 1940, an even worse change came to the operational maps. The Germans conquered Denmark, so providing a gate to the Baltic, and Norway, with its bases and access to the North Atlantic. The only alleviation of this gloom was that the Norwegian merchant fleet – one of the world’s largest – sailed to England to evade the Germans. This enormous addition to the shipping tonnage was to become the margin by which Britain survived in the dark days to come.
When in the summer of 1940 France was conquered by the Germans its fleet did not sail to British ports to continue the fight. In the Atlantic and Mediterranean the Royal Navy took on the whole load the French navy had shared. France’s Atlantic coast also provided magnificent submarine bases, well away from RAF bomber airfields. From these ports the U-boats could sail directly into the world’s oceans.
When Admiralty radio interceptions and bearings indicated that U-boats were using French ports the Foreign Office insisted that it was impossible; the French would not permit it. Lt Minshall RNVR, the same young officer who had provided the globe for the Admiralty, volunteered to investigate. One of the Royal Navy’s submarines took him to the French coast, where he spotted and commandeered a French boat which he sailed into the mouth of the Gironde. He stayed there for six days, noting the U-boat movements and enough details to convince even the men of the Foreign Office that the ports were being used.12 He got back to England in the sailing boat and was awarded a ‘mention in dispatches’.13
Britain’s armed forces had gone to war expecting to fight in the way they had fought in 1914. The British Expeditionary Force would go to France and hold a small section of the Western Front while the Royal Navy – aided by the French fleet – protected the sea routes and waited to re-fight the battle of Jutland. Now everything was changed. Britain was isolated and the Germans held most of Europe, including the Channel coast just twenty-one miles away. With Italy fighting alongside Hitler the Mediterranean sea routes were fiercely contested and Britain’s army in Egypt was under constant threat. By the summer of 1940 no one could continue to believe that this war would much resemble the previous conflict.
Cracking the naval codes: Enigma
In 1920 the organization known in the First World War as I.D. 25, and usually referred to as Room 40, changed its name to the Government Code and Cypher School (GC&CS). This name served to hide its true purpose, which was to protect British official communications and intercept foreign ones. It was a part of the Secret Intelligence Service, and in 1925 it was moved from a building behind Charing Cross railway station to the SIS headquarters at 54 Broadway, London, near St James’s Park underground station, a site conveniently close to the Foreign Office. A few days before the outbreak of war its name was again changed – to Government Communications Headquarters – and it moved to an endearingly ugly but conveniently secluded Tudor-Gothic Victorian house at Bletchley Park, about fifty miles north of London. Its principal task was to read German radio messages encoded on Enigma machines.
The Enigma started its career as a commercial enciphering machine, a sort of typewriter that scrambled text using notched wheels or rotors. The message could be unscrambled by a recipient using an identical Enigma with its rotors adjusted to the same settings, known only to the sender and the receiver. When the Germans bought some Enigma machines they adapted them to make them more difficult to counter. The improved machine had plugs, varying the circuits, which the operators changed every twenty-four hours according to a dated instruction book of ‘keys’. This gave an astronomical number of alternatives for each letter.
The story of the breaking of the Enigma can be said to start in October 1931, at the Grand Hotel, Verviers, a town in Belgium not far from the German border. Hans-Thilo Schmidt, a highly placed official in the German Defence Ministry, made contact with Rodolphe Lemoine, an agent of the Deuxième Bureau, the French military intelligence service. Lemoine, a widely travelled linguist, had been born in Berlin, the son of a jeweller. A naturalized French citizen, he had taken his French wife’s name and, despite being a successful businessman, he went to work as a secret agent. Lemoine got along well with his fellow Berliner. Schmidt’s father was a professor and his mother a baroness, but this highly intelligent and well educated veteran of the First World War found it difficult to manage on the salary he earned as a clerk distributing cipher material. He offered to sell the operator’s instruction manual for the Enigma machine and some other notes and manuals. He also offered to continue to supply information about the updating of the machine and its codes as well as details of the workings of the German High Command (where Schmidt’s elder brother was now a lieutenant-colonel and chief of staff of the signal corps). At one time Rudolf had been the head of the cipher section – Chiffrierstelle – where Hans-Thilo now worked, and it had been Rudolf’s decision to purchase the Enigma machines that his brother was offering to compromise.
FIGURE 5
German Enigma coding machine
It was Lemoine’s stated belief that every man had his price, and at their first meeting he offered Hans-Thilo Schmidt payments equal to three times what he was getting in salary. The Service de Renseignement in Paris approved the deal and gave Schmidt the codename HE, which spoken in French eventually gave way to the German word Asche, ash. Although the material from Hans-Thilo enabled the French to read a few messages, the complex wiring inside the machine made it a daunting challenge. Paris, deciding that cracking such a machine was beyond their resources, offered to share the task with the British, but the Secret Intelligence Service in London was not interested. The French decided to give everything they had collected to the Poles.
The successes of French and British linguistic cryptanalysts, working on methods perfected during the First World War, persuaded their masters to ignore the problems of mathematical cryptanalysis. This was why the Enigma machine defeated them. The Poles had superior mathematicians, more men familiar with the German language, and the will to succeed at a task no one else believed possible.
By 1933 the Poles had rigged up a reproduction of the Enigma. They kept the French informed about their progress and the French faithfully passed to Warsaw the new codes and whatever mechanical changes to the machine Hans-Thilo could discover. However over a period of five years few of these messages got to the codebreakers. The Polish high command wanted its men to crack the German codes without outside help, and it doled out the material from Hans-Thilo only in small amounts when the codecrackers were stuck.
The Germans improved their coding machines while the Poles improved their codecracking ones, constructing what they called a bombe, a computer consisting of six linked Enigma machines. In September 1938 the fears of the Polish intelligence chiefs came true. Hans-Thilo was transferred to Göring’s Forschungsamt and the supply of codes ended. But by now the codecrackers had learned to manage without his help.14
On 24 July 1939, with war not far away, the Poles invited the French and the British to Warsaw to show them in great detail the work they were doing breaking the German codes. They showed them the bombe, a method of using overlaid perforated sheets, and calculations about wiring. Mathematical talent was at the heart of the Polish work. Some of the most notable breakthroughs had been made by Marian Rejewski, a young mathematician who has been described as one of the greatest cryptanalysts of all time.15
As a going-away present both French and British representatives were given a ‘replica’ Enigma machine. Although as the Germans got nearer to war they changed the codes, and added an extra rotor to their Enigmas to make the machine codes more complex, this gift was beyond price. Gustave Bertrand, a senior French intelligence officer, described how he brought the machine to the chief of Britain’s Secret Intelligence Service.
On 16 August 1939 I was on my way to London accompanied by Uncle Tom – the diplomatic courier of the British Embassy in Paris – who was carrying a diplomatic bag with the Enigma machine. At Victoria Station Colonel Menzies, head of the [S]IS wearing the rosette of the Legion of Honour in the buttonhole of his dinner-jacket (he was going to a soirée) was waiting for us: triumphal welcome! Which occasioned him to say one day [that the French intelligence service] had done him a ‘considerable service on the eve of the war’.16
Considering how little accurate information his SIS was able to supply about even peacetime Nazi Germany, the ill-judged rejection of the French offer of the Enigma secrets and a total lack of any preparations for war, Colonel Menzies did not exaggerate.
Poland was invaded, but keeping ahead of the Germans the Polish codecrackers moved to France. Then France fell too. The French team escaped the German invaders, set up shop near Uzès in the unoccupied sector of France, and continued their work, sending their solutions to London (enciphered in Enigma!). Many Polish and French cryptologists ended up as captives of the Germans, but all managed to convince their interrogators that Enigma was beyond their abilities. The Germans believed them; such is the power of self-deception.
In 1943 some Polish members of the original team reached England after harrowing experiences. According to one notable historian of the Enigma story: ‘The Poles reaped the customary reward of the innovator whose efforts have benefited others: exclusion. The British kept Rejewski and the others from any work on Enigma, assigning them instead to a signals company of the Polish forces in exile, where they solved low-level ciphers. It was not one of Britain’s finest hours.’17
Bletchley Park was sited halfway between Oxford and Cambridge universities, and with more and more big wooden huts built in the grounds, GC&CS were able to recruit and accommodate academics including the junior dean and mathematical tutor of Sidney Sussex College who arrived on the first day of war. Hurrying back from an International Chess Olympiad in Buenos Aires came Britain’s chess team. More such men and women followed.
No one in the world had ever attempted to break machine-enciphered messages on a regular basis with all the urgency that war brings to such a task. The resulting intelligence – eventually to be called Ultra – came solely from radio transmissions in Morse code. No teleprinter message or telephone conversation was included, and since most of the vital messages were sent by those means, the greater proportion of secret enemy communications were never intercepted. Sometimes a radio message in Enigma was answered by telephone or teleprinter, or vice versa, so that only one side of a dialogue was available. Radio reception was often subject to interference, and errors were commonly included, making the job even more perplexing.
The British took up where the Poles left off. The first break-throughs came from analysis of the uncoded message prefixes that told the recipient the key settings for the Enigma machine. Analysing the electrical wiring in rotors and plug boards, mathematicians and ‘probability specialists’ soon ‘reduced the odds against us by a factor of 200 trillion’.18 However there was still about a million to one against the men trying to conquer the Enigma messages. Wheel order and ring settings, the two most vital secrets, were sometimes guessed at by ‘sheet stacking’, a technique the Poles had pioneered. Holes – one per letter – punched in large sheets of paper allowed light through to reveal the pattern of the day’s key.
The repetitive phrases used in much of the traffic also helped: especially the formal way in which people and organizations were addressed in full. Often the codebreakers were waiting for the Germans to describe something that had already happened, such as a bombing attack or a weather report. Sometimes the same message was sent in a low-grade code – already cracked – and in Enigma too. In that case the two messages could be compared.
From time to time a rotor or two was retrieved from the pocket of a rescued U-boat crewman. By summer 1941 much-improved bombes came into use at Bletchley Park. These were 10-feet-high electro-mechanical machines like calculators. Using rotors like those inside the Enigma machines, the bombe searched rapidly through, not every possibility but the limited number chosen by the operator. The clickety-clickety sound came to a sudden stop when the bombe found a letter substitute for which the operator was looking. This would provide a setting that could be tried on a British encoding machine that had been adapted to perform like an Enigma. The printer started and produced a long strip of text. If it was ‘a good stop’ it might mean a batch of messages could be broken.19
If it was a navy message it would then go to the Royal Navy section in one of the huts, where a dozen or more men juggled with the German military jargon to make an intelligible message in English. This done, English and German versions might be sent by teleprinter to the Submarine Tracking Room in the OIC (Operational Intelligence Centre) in the Admiralty’s Citadel near Trafalgar Square in London.
The ‘key’, the settings of the rotors and the plugs, changed daily, or sometimes every two days. It was the most difficult problem, but even after the settings were discovered, the deciphered messages still had to be translated and made intelligible. Many messages were long, and included codenames and complicated service references that would be baffling to any civilian. There were technical aspects of stores, requisitions, meteorology, aviation or maritime matters. There were newly minted technical words and acronyms. A great deal of the intercepted material was banal and of little or no possible use as intelligence. And of course everything was in German. For some messages a result in two or three days was too late, and this was usually the case with the constantly moving war at sea.
The military wisely gave way to the boffins in the matter of getting useful results quickly. The first stage was a job for mathematicians; the second stage for men who spoke German. One of the Bletchley Park team remarked:
The rise to prominence of the translators – their pivotal position was already an accomplished fact by the winter of 1940–41 – inaugurated a revolution which gave primacy to the end over the beginning.20
A navy, army or air expert assessed and annotated the translation to underline its significance. He would add, for instance, references to a unit, a place or person mentioned, bringing into use the big card-reference system that each service maintained. The next stage was the drafting of a signal to the field commander who could make use of the intelligence. The syntax of the message was changed, or ‘sanitized’, so that if the Germans encountered it they would not be able to identify the original message and guess how it had been obtained.
The British army monitors at Chatham, on the Thames Estuary, and later other stations too, listened to all German short-wave radio traffic. According to the weather, reflections from the upper atmosphere would sometimes enable transmissions from U-boat to U-boat in the farthest reaches of the Atlantic to be heard.
The Enigma coding machine was a remarkable invention. The most surprising aspect of the story is that the experts agree that a few simple changes to the original design could have made it fool-proof in use, and its output totally invulnerable. Messages were usually broken because of German carelessness and lax procedures. The Luftwaffe provided most opportunities; the navy was far more careful, so the German navy’s Enigma codes were not broken on anything like a regular basis. A founder member of the Bletchley Park team commented: ‘At any time during the war, enforcement of a few minor security measures could have defeated us completely.’21
In any case it wasn’t necessary to understand what a message said to benefit from knowing where your enemy was. High Frequency Direction Finding (HF/DF or what the Royal Navy called ‘Huff Duff’) could estimate the position of U-boats (or enemy surface ships) by getting a compass bearing on the transmissions. BP staff also made valuable assessments of German preparations and operations by studying the volume, character and point of origin of signals traffic.
Oscilloscope patterns (which depict voltage or current fluctuations on a cathode ray tube) were also photographed and filed to provide a ‘fingerprint’ that could positively identify a radio transmitter, and this in effect was enough to identify a ship or U-boat. Such fingerprinting was another of Lt Merlin Minshall’s ideas. It was in this way that the Bismarck was positively identified.22
Britain’s Secret Intelligence Service retained control of their GC&CS, and so deciphered material went to their Broadway HQ for distribution to whoever ‘C’ – Colonel Stewart Menzies, the organization’s chief – thought deserving. The Royal Navy did not trust SIS with this task, and right from the beginning the navy kept its facilities at Bletchley Park entirely separate from those of the army and the RAF. The admirals had not been satisfied with SIS since November 1939 when Menzies, an army man, was appointed to be ‘C’. The navy said that previous SIS chiefs – Captain Smith-Cumming and Admiral Sinclair – had established a tradition that ‘C’ would always be a job for a sailor.
So all naval material was handled independently and went to the OIC (Operational Intelligence Centre) in Whitehall. In early 1941 the OIC moved to the Citadel (a lumpy brown granite building between Admiralty Arch and Horse Guards; it is still there, mercifully hidden under ivy).
The navy’s system worked reasonably well. By the end of July 1941 – due largely to the capture of some Enigma machine rotors and dated settings in February, March and May – there was regular interception of Enigma signals. These were being added to all the other signals intelligence, collectively known as SIGINT, which included data from diplomats, foreign newspapers and secret agents, as well as from interrogating, bugging and planting stool-pigeons among captured U-boat crewmen. It was all analysed and put together, and with these sources the Admiralty’s Submarine Tracking Room tried to predict the intention of the U-boat captains.
Radio transmissions from U-boats were few and far between. Getting one solitary fix on a U-boat simply put a coloured pin into a big plotting table. From that there was no telling which way the submarine was heading. Was it outward-bound, with a full complement of torpedoes, or was it limping home with engine troubles? Or was it part of a ‘rake’ of other U-boats across the expected route of a convoy? The Submarine Tracking Room – using all its resources – tried to answer such questions, often guessing right and telling transatlantic convoys to change route and avoid the places where the U-boat packs were waiting. This rerouting of convoys was to become the most effective counter to the U-boats, and – since signals avoided all references to German movements – it was unlikely to reveal British successes with Enigma.
By 1941 the German armed forces had thousands of Enigma machines in use. One of the disadvantages to such machines was that they could be lost or stolen, and so could the keys, the settings for rotors and plug boards. Ever since the remarkable luck of finding some Enigma settings in the patrol boat VP2623, captured off Norway long before in April 1940, the codebreakers had been crying out for more.
On 23 February 1941 during a commando raid on the Lofoten Islands, northern Norway, the destroyer HMS Somali fought off a suicidal attack by a tiny German trawler, Krebs, which was left holed and beached. The Somali’s signals officer volunteered to search the little ship. From it he got some spare rotors and the Enigma ‘keys’ for the month of February. It was a splendid haul, more important to the war than the destruction of ships and factories and oil that had been the purpose of the commando raid.
It wasn’t the rotors found on Krebs that pleased the men at BP (Bletchley Park) – they already had them. The keys however were very valuable; with them current messages could be read without any delay. Even outdated keys were useful, enabling older messages to be examined. Such keys were always printed in water-soluble ink, and a dousing in seawater was enough to render them illegible. Ian Fleming, later to gain fame as the creator of James Bond, was at this time in naval intelligence and he came up with a hare-brained scheme to get some more of these keys. A captured airworthy German plane would be crash-landed in the sea and (it was hoped) found by a German ship. The rescued airmen would thereupon seize control of the ship and grab its codes. It says a lot about the desperate need for settings that this idea was taken seriously and a captured Heinkel made ready. Fortunately one of the boffins came up with a more practical adventure. The bounty of the February intercepts revealed that German weather-ships out in the Atlantic used Enigma. It also disclosed their movements. Why not capture one of those? The weather-ships were on station for months, so they might have longer lists of keys.
The destroyer Somali was used also in this engagement, which depended upon closing on the little weather-ships as quickly as possible in the hope that not everything would be tossed overboard. In the case of the weather-ship München the seizure and boarding went according to plan, and among the bundles of paperwork seized there were German Enigma keys for June. This would not enable the Bletchley Park men to read the whole of German naval traffic, for the navy had many different keys. But now the important ‘home waters’ radio traffic would be available. A second weather-ship, the Lauenberg, was intercepted on 28 June, just as the next month’s settings were due to come into use. Now traffic up to the end of July could be read.
By this time there had been another dramatic success in the story of Enigma. It was early morning on Friday 9 May 1941 and the outward bound convoy OB 318 was seven days out of Liverpool. There was reason for the British sailors to feel that the most hazardous part of the voyage was done; no U-boat had made a kill this far west. But trailing the convoy came U-110, one of the big long-range Type IX submarines. It was commanded by Kapitänleutnant Lemp, the man who sank the passenger liner Athenia in the first hours of the war. He now wore the Knight’s Cross – or ‘tin tie’ – at his collar. With him to the U-110 he had brought his cousin, who was regarded as a Jonah by the crew, after having two previous boats sunk under him.
In daylight, submerged, Lemp fired three torpedoes. Two merchant ships were hit. One ship’s stern tipped up so steeply that crates on her deck rolled into the ocean like ‘a child pouring toys out of a box’.23 One of the convoy’s escorts spotted the racing white wake of his periscope, sped towards it and dropped a pattern of depth charges. But Lemp escaped and without delay came back up to periscope depth just in time to see the destroyer coming at him. The second scatter of depth charges was close. The underwater explosions stopped the electric motors, started leaks in the oil bunkers and sent the U-boat plunging downwards. Lemp ordered the tanks blown. This not only stopped the descent but brought U-110 back up to the surface with a boiling of water that got the immediate attention of the deck crews of all three destroyers. Flustered, Lemp failed to have the pressure valve released, so that when the hatch opened a great cloud of dust came pouring out of the submarine. So did the crew, who jumped into the sea with their captain.
The captain of HMS Bulldog was shouting for a boarding party almost as soon as the mortally damaged U-110 surfaced. Ignoring the probability that the Germans had set explosives before abandoning ship, a 20-year-old sub-lieutenant, rowed out by five sailors, clambered aboard the slippery hull of the wallowing boat and went down into the dark interior followed by his men. They formed a human chain to pass back the codebooks, charts and, having unscrewed it from its mounting, the Enigma machine itself. With great thoroughness and an iron nerve the sub-lieutenant scoured through everything on the U-boat from charts to ‘art studies’. He searched through discarded clothes to find anything of value to intelligence from the contents of wallets to recreational reading matter. It took three or four hours to get everything valuable aboard Bulldog.
