The Secret War: Spies, Codes and Guerrillas 1939–1945

When the international horizon darkened, on what proved Turner’s final visit to Germany Mayer told him that if war came, he would try to supply Britain with information about German scientific and technological progress. In late 1939 the scientist exploited a chance business trip to Norway to make good on his promise. He borrowed an old typewriter from the porter at the Hotel Bristol and composed the ‘Oslo Report’, which was dispatched in two parts to the British embassy on 1 and 2 November. Mayer also wrote directly to Cobden Turner, suggesting further contact through an intermediary in neutral Denmark. But although this letter caused two British security officers to visit and question the GEC man, for reasons unknown nothing was done to open communication with Mayer – MI6’s official history makes no mention of this courageous German. In August 1943 Mayer was arrested by the Gestapo in his office at Siemens, and charged with listening to the BBC. He was confined in Dachau, but was fortunate enough to be employed in a technical plant, where he survived the war. His brave gesture was prompted by admiration for Cobden Turner, whom he liked to regard as a representative Englishman. Recognition of Mayer’s contribution, however, came only from Reg Jones.

Among the reasons the ‘Oslo Report’ received such a chilly reception is that it was debated in Whitehall just as the British secret community reeled in the wake of a successful German ruse. On 9 November 1939, during the first, passive phase of the war that became derisively known as the ‘sitzkrieg’, the two senior MI6 officers in the neutral Netherlands, Captain Sigismund Payne Best and Major Richard Stevens, drove with a Dutch officer in Best’s Lincoln Zephyr car to a rendezvous at the Café Backus, situated between the Dutch and German border customs barriers at Venlo. Within minutes of their arrival, they were seized by armed men. When the Dutchman drew a pistol and fired at one assailant, he was himself shot dead. Best, Stevens and their local driver were then hustled 150 yards to the frontier: their kidnappers were Nazi counter-intelligence officers of the SD, led by the branch’s later boss, Walter Schellenberg, who was narrowly missed by the Dutch officer’s bullet. The British spies were fortunate enough to keep their lives, but spent most of the rest of the war in Sachsenhausen concentration camp. In contradiction of myths about heroic silence under interrogation, Stevens and Best told their abductors what they knew about MI6, which was plenty: its Continental operations were chiefly conducted from their own Hague station.

‘The Venlo incident’, as it became known in Whitehall, derived from an approach some weeks earlier by supposedly anti-Nazi German generals eager to negotiate with Britain. MI6 became much excited by the prospect of brokering a deal, though the Foreign Office was prudently sceptical. Sir Alexander Cadogan wrote in his diary on 23 October: ‘I think they [the German “plotters”] are Hitler agents.’ The war cabinet was informed a week later, and Winston Churchill, then still First Lord of the Admiralty, expressed violent objections to any parley. But the government authorised MI6 to continue discussions, provided – as Cadogan strictly instructed – nothing was put in writing to the supposed dissidents. The British ignored the danger that their interlocutors would play not merely a diplomatic game with them, but a rougher one. They should have been alert to such an outcome, because the Nazis had previous form as cross-border kidnappers: in April 1934 they had lured to the German frontier a Czech intelligence officer, twenty-nine-year-old Captain Jan Kirinovic, then rushed him across. A Gestapo witness gave evidence at Kirinovic’s subsequent trial that he had been arrested on German soil, and Kirinovic was sentenced to twenty-five years’ hard labour. Although in the following March the Czech officer was exchanged for two German spies, he died insane a few years later as a result of the drugs administered to him by the Gestapo, notably scopolamine.

In November 1939, it was symptomatic of MI6’s institutional weakness that its Hague station employed Folkert van Koutrik, an Abwehr informant. The supposed representative of the disaffected German generals, ‘Major Schaemmel’, was in truth the RSHA’s Schellenberg, whom the British officers obligingly supplied with a wireless transmitter. Either Hitler or Himmler personally authorised the kidnapping, which the British at first sought to keep secret. When an official asked Cadogan what was to be said about ‘the brawl in Holland’, the subject of fevered rumour and speculation, the permanent under-secretary ordered the issue of a ‘D’ Notice, forbidding mention of it in the British press. Amazingly, for a fortnight after Venlo the German ‘conspirators’ sustained a dialogue with MI6, until on 22 November Himmler lost interest and the Germans shut down the exchange after sending a last derisive message to Broadway. The Nazis then publicly announced that Best and Stevens had been engaged in an assassination plot against Hitler. Meanwhile van Koutrik’s betrayal went so far undetected that he secured employment with MI5 in London, and it was very fortunate that he broke off contact with the Abwehr – perhaps for lack of means of communication – because it was within his later knowledge to have betrayed elements of the Double Cross system to them.

Inside Whitehall, MI6 sought to talk down Venlo, arguing that the Germans had behaved crassly by grabbing the two officers instead of sustaining a double-cross game with them. It is hard to overstate the episode’s significance, however, for the future course of the secret war. British espionage activities on the Continent, such as they were, suffered a devastating blow: the Germans were able to relieve Best of a list of his station’s contacts, which he had taken in his pocket to the rendezvous. The reputation of the secret service within the British government, not high before the débâcle, afterwards sagged low indeed. Guy Liddell of MI5 speculated in his diary that Best, a preposterous figure who affected a monocle, might have been a double agent – ‘the real nigger in the woodpile. [He] had apparently been in fairly low water and it was noticeable that after he became associated with [Dr Franz] Fischer [a Nazi double agent in Holland] he seemed to be very well in funds.’ There is no reason to think Liddell’s suspicions justified. Mere bungling was responsible for the fiasco, though Walter Schellenberg asserted later that Best was willing to be ‘turned’. Meanwhile, the Dutch were embarrassed by the revelation that one of their own intelligence officers had been complicit in a British plot, which strengthened the Nazis’ propaganda hand by compromising Holland’s proclaimed neutrality.

A further consequence of Venlo was that the British became morbidly suspicious of any approach – and there were several, later in the war – by Germans professing to represent an ‘anti-Hitler Resistance’. In one sense their caution was prudent, because most of the aristocrats and army officers who became engaged in plots against the Nazis cherished absurd fantasies about the Germany they might preserve through a negotiation with the Western Allies. Former Leipzig mayor Karl Gördeler, for instance, was a nationalist with views on German territorial rights in Europe that were not far short of Hitler’s. Even had the Führer perished, there would have been nothing plausible for Germany’s enemies to discuss with his domestic foes. At the very least, however, British paranoia about suffering a repeat of the Venlo humiliation permanently excluded MI6 from some useful sources, which the Russians and later the Americans were left to exploit. Moreover, for the rest of the war Broadway’s chiefs maintained an exaggerated respect for their German adversaries, derived from the memory of having been fooled by them in November 1939.

Through the icy winter months of the ‘Phoney War’, the GC&CS at Bletchley struggled with the intractable Enigma problem, while Broadway’s spies produced little or no useful information about the enemy and his intentions. Kenneth Strong of War Office Intelligence wrote: ‘We had a continuous stream of callers from the Services with an extraordinary variety of queries and requests. What were the most profitable targets for air attacks in this or that area, and what effect would these attacks have on the German Army? Was our information about these targets adequate and accurate? How was the German Army reacting to our propaganda campaigns? I found some quite fantastic optimism regarding the effects from propaganda. The dropping of leaflets was considered almost a major military victory.’

Some MI6 officers went to elaborate lengths to conceal their lack of agent networks. Reg Jones cited the example of Wilfred ‘Biffy’ Dunderdale, who was responsible for France, and fed to Jones’s branch a succession of tasty titbits on the German Ju-88 bomber, allegedly collected by spies. First there was information about its engines; then its electrics; and somewhat later its armament. Jones teased Dunderdale that he must have secured a copy of the aircraft’s operating handbook, then fed extracts to Broadway, to create an impression of multiple sources. The hapless officer admitted that Jones was right, but begged him to keep his mouth shut. He could keep his bosses much more interested, he said, by drip-feeding the data. This was not the only occasion when Dunderdale – like officers of all intelligence services – sought to ‘sex up’ the means by which his material had been acquired. He also produced details of German troop movements supposedly secured by agent networks, which in reality derived from French intercepts.

Much could be learned from an enemy’s wireless transmissions, even without breaking his codes, through ‘traffic analysis’ – the study of signal origins, volume and callsigns to pinpoint units, ships, squadrons. Useful information was also gleaned by the ‘Y Service’, eavesdropping on voice transmissions, and by breaking simple enemy codes used for passing low-grade messages. The French forward cryptographical unit was based at ‘Station Bruno’, in the Château de Vignobles located at Gretz-Armainvilliers, fifteen miles east of Paris. Bruno received an important reinforcement following the fall of Poland. Guy Liddell of MI5 recorded on 10 October 1939 that seventeen Polish cryptanalysts were seeking asylum in Britain. Bletchley Park shrugged dismissively that it had no use for them, even though its chief Alastair Denniston had met some of the same men in Warsaw a few months earlier, and knew that their claims to have penetrated Russian and German ciphers ‘can to some extent be maintained’.

Denniston suggested that they would be more useful at the Château de Vignobles, working with Gustave Bertrand, which was where they were sent – though Bletchley later changed its mind and tried in vain to get them back. It was at Bruno, on 17 January 1940, that the ex-Warsaw group broke its first wartime Enigma signal. By 11 March Col. Louis Rivet, head of the French secret service, was writing in his diary: ‘The decrypts of the Enigma machine are becoming interesting and numerous.’ During the months that followed, however, material was read far too slowly – out of ‘real time’ – to influence events on the battlefield. Instead, Allied intelligence officers strove to make sense of a jumble of humint warnings, of varying degrees of plausibility, about when Hitler intended to strike in the West.

The first of these had come in the previous November when Major Gijsbert Sas, Dutch military attaché in Berlin, received a dramatic tip-off from his friend Colonel Hans Oster of the Abwehr: the Wehrmacht, said Oster, would launch a full-scale offensive against the British and French armies on the 12th of that month. This coincided with several other identical or similar warnings – including an important one from Col. Moravec’s Czechs in London, relayed by their man in Switzerland from Agent A-54, the Abwehr’s Paul Thummel. When nothing happened on 12 November, the British and French chiefs of staff assumed that they were the victims of Nazi disinformation. The Dutch already suspected Sas of being a double agent, and the credibility of the other sources, including A-54, suffered accordingly. Yet the warnings were correct. Hitler had indeed intended to strike in November. He was enraged that his generals insisted upon a last-minute postponement until spring, because the army was unready to move. Here was a vivid illustration of a precept later advanced by a British Army intelligence officer: ‘Perfect intelligence in war must of necessity be out-of-date and therefore ceases to be perfect … We deal not with the true, but with the likely.’

The next excitement took place one day in January 1940: thick fog caused a German courier aircraft flown by Major Erich Hönmanns to forced-land in neutral Belgium. Local police arrested the pilot and his passenger, an officer named Reinberger, interrupting them as they attempted to burn papers they carried, and retrieved the charred sheets from a stove. Within forty-eight hours the French and British high commands were reading the Wehrmacht’s plan for its intended invasion of France and the Low Countries, focused on a thrust through Holland and Belgium. Here was a textbook example of a genuine intelligence coup, with wholly unhelpful consequences. The French were confirmed in their conviction that the Germans would attack through Belgium as they had done in 1914, and as all France’s deployments anticipated. The British suspected an enemy deception: the material seemed too good to be true. Guy Liddell of MI5 wrote wearily on 14 January: ‘A German aeroplane came down in Belgium … with certain papers found on the pilot indicating projected attack by the Germans on Belgium and Holland. It looks rather as if this may have been part of the scheme for the war of nerves.’ Cadogan at the Foreign Office described receiving ‘complete plan of German invasion of the Low Countries. Very odd. But one can’t ignore these things, and all precautions taken.’

Kenneth Strong wrote ruefully afterwards: ‘So often I have heard it said that if we only had the plans of the other side things would be simple: when they actually came our way we found great difficulty in persuading ourselves that they were genuine.’ Most important, however, the capture immediately forfeited all virtue, because the German proprietors of the plan knew that the Allies had it. Thus, Hitler insisted on changing the invasion concept, to thrust instead through the Ardennes, which proved the one authentic strategic inspiration of his life. Here was another critical lesson about intelligence, especially important for codebreakers: captured material became worthless if its originators discovered that it was in enemy hands.

Alexander Cadogan noted in his diary for 19 January 1940 that Stewart Menzies now seemed to expect the Germans to attack soon after 25 January, and added dismissively, ‘but he’s rather mercurial, and rather hasty and superficial (like myself!)’. If this remark somewhat short-changed the diarist, it was scarcely a ringing endorsement of ‘C’. There was one further strand: low-grade Abwehr messages decrypted by MI5’s Radio Intelligence Service offered indications about the looming onslaught. At that time, however, machinery was lacking to analyse such material, to feed it into the military command system and ensure that notice was taken by commanders. In that pre-Ultra universe, politicians, diplomats and generals were chronically sceptical about intelligence of all kinds. When a new warning reached MI6 via Moravec’s ‘London Czechs’ – that Abwehr officer Paul Thummel expected a great Wehrmacht thrust on 10 May, it vanished in the welter of ‘noise’ that spring.

The 9 April German invasion of Norway caught the Western Allies totally by surprise. Though no decrypts were available, the Admiralty ignored or misread plentiful clues about Hitler’s intentions. When the Wehrmacht’s amphibious forces began to land on the Norwegian coast, the Royal Navy’s major units were far away, awaiting an anticipated breakout into the Atlantic by German battleships. Through the weeks that followed, Wehrmacht eavesdroppers easily tracked the British brigades struggling to aid the little Norwegian army, while intelligence learned little or nothing about the invaders’ lightning movements.

On 10 May 1940, Hitler launched his Blitzkrieg in the West. The panzers swept through the Ardennes, across the Meuse, and thence to the Channel coast and into the heart of France. Much of the information sent back from the front by French units was so fanciful that a headquarters intelligence officer, André Beaufre, dismissed it contemptuously as a ‘fiction flood’. Gen. Maurice Gamelin, the Allied commander-in-chief, rejected every report that contradicted his obsessive belief that the Germans still planned to make their main attack through Belgium.

The campaign proved a triumph for the German army’s intelligence department, as well as for its generals. An anglophile and bon viveur, Lt. Col. Ulrich Liss, headed Foreign Armies West – FHW, the Wehrmacht’s principal intelligence evaluation department. Liss, who was exceptionally able and energetic, called sigint ‘the darling of all intelligence chiefs’, because it could be trusted as spies could not – and in May 1940 the best of it was in the hands of his own staff. During the long, static winter, German interceptors had identified the locations of most of the Allies’ formations, much assisted by the insecurity of the French army’s wireless-operators and headquarters staffs, who often discussed plans and deployments in plain language. Col. Handeeming, radio intelligence’s interception chief with Army Group A, was explicitly commissioned to monitor the French Seventh Army’s advance into Belgium, which he did with notable efficiency.

Liss’s men also benefited from securing vast numbers of Allied prisoners. All armies gleaned much from PoW interrogation. Throughout the war, even if few prisoners knowingly betrayed secrets, amid the shock of capture most gave their captors more than the regulation ‘name, rank and number’. Rommel’s intelligence staff found that British prisoners talked freely until a late stage of the North African campaign. One of Montgomery’s officers enthused to the Germans, with almost insane indiscretion, that Eighth Army’s radio monitoring service was ‘brilliant in every respect’. A German wrote that British officers were repeatedly captured ‘carrying important lists, codes and maps’. It was a standard technique for intelligence officers to engage PoWs in apparently innocent conversation about non-military subjects. The Wehrmacht’s ‘Guidelines for the interrogation of English prisoners of war’, dated Berlin, 16 April 1940, urged commanders whenever possible to use interrogators familiar with Britain and the British. ‘If cordially addressed,’ said the briefing note, ‘every Englishman will at once answer all questions entirely frankly.’ Beyond immediate tactical issues, the Intelligence Department advised:

Special value is set on probing prevailing economic and social circumstances in England. Answers to the following questions are useful:

a) What are you told about Hitler?

b) What are you told about the Nazis?

c) What are you told about the Gestapo?

d) What are you told about the Jews?

e) What are you told about food conditions in Germany?

f) What are you told about military successes?

g) How do you make propaganda?

h) How are women and children cared for?

i) Do you take care of elderly parents no longer able to work, whose sons are soldiers? …

k) What is the food situation – especially meat, vegetables, eggs, butter, and bread?

l) What do you think of the black-out?

m) Who is currently the most popular man in England?

n) Who do you consider the most forceful personality in the British cabinet?

o) Do you listen to German radio?

p) Do you like [Lord] Haw-Haw [the Nazi propaganda broadcaster William Joyce]?

q) How are your relations with the French?

r) Do you believe that Germany is bent on world conquest?

s) Would you make peace tomorrow?

The behaviour of most PoWs was strongly influenced by their own nation’s immediate circumstances. At this time, when Allied fortunes were plumbing the depths, a report on the handful of German PoWs in British hands recorded gloomily: ‘The officers (and most of the men) were quite immune to propaganda, think Hitler is a god and refuse to believe a single word of the British news.’ By contrast, a South African RAF pilot named Sgt Edward Wunsch provided his German captors with a highly sympathetic view of the Nazi cause, as recorded by his interrogator: ‘Like all South Africans who have entered Dulag Luft, Wunsch is an unashamed anti-Semite … [He says] There is no hatred towards Germany in South Africa, no enthusiasm for the war at all. Most people believe the nonsense press and propaganda tell them about German atrocities but … W. thinks it possible that one day South Africa could agree to a separate peace, if Germany continues to be militarily successful [author’s italics].’

The Allies lost the 1940 battle for France for many reasons. It has been a source of fierce controversy ever since, whether the French army’s defeat resulted from a failure of judgement by Maurice Gamelin, Allied commander-in-chief, or instead from a national moral collapse. It is unlikely that any amount of intelligence or advance warning could have changed 1940 outcomes. The German army showed itself an incomparably more effective fighting force than the Allies’, and there would be no victories until that changed. If British and French intelligence was poor in 1940, so was everything else.

As the Continent was evacuated, there was a late flurry of buccaneering by secret service officers and freelances: MI6’s Major Monty Chidson, a former head of the Hague station, rescued a priceless haul of industrial diamonds from Amsterdam. Peter Wilkinson got most of the Polish general staff out of France. Tommy Davies, a peacetime director of the Courtaulds textile business, escaped from its Calais plant with a load of platinum hours before the Germans arrived. But these little coups were fleabites in the great scheme of affairs. MI6 had made no contingency plans for stay-behind agents, to report from France in the event of its occupation by the Nazis, and Broadway would probably have been accused of defeatism had it done so. Through many months that followed, Britain’s intelligence services were thus almost blind to events on the Continent, to the frustration of the prime minister. Beleaguered on their island, they became dependent for knowledge of Hitler’s doings on the vagaries of air reconnaissance, and reports from neutral diplomats and correspondents.

The security service explored the limits of the possible and the acceptable in handling a stream of Abwehr agents who descended on Britain, and were promptly captured. MI5 spurned torture as a means of interrogation: in September 1940 at Camp 020, one of its officers intervened to prevent the captured Abwehr agent ‘Tate’ – Harry Williamson – being assaulted and battered by Col. Alexander Scotland of MI9. Guy Liddell deplored this episode, saying that he objected to ‘Gestapo methods’ on both moral and professional grounds. Col. Scotland was likewise prevented from injecting Williamson with drugs. Naval Intelligence Division interrogators tested drugs on each other as a means of extracting information, and concluded that it was a waste of time. Skilled questioning, they decided, was not merely more ethical, but more effective.

As the next act of the great global drama unfolded – Hitler’s air assault on Britain – neither Broadway nor Bletchley Park had much to contribute. The most significant aid to Fighter Command in its epic struggle to repel Göring’s air fleets was wireless traffic analysis of the flood of Morse from the Germans’ new French, Belgian, Dutch and Norwegian bases, together with monitoring of Luftwaffe cockpit chatter by the German linguists of the RAF’s infant Y Service, most of them women.

The prime minister and the chiefs of staff were for many months preoccupied, even obsessed, by two questions: would the Germans invade; and if so, when? In the mad mood prevailing in London in the autumn of 1940, a blend of heroic defiance and absurdity, the War Office’s director of military intelligence suggested exploiting captured Abwehr agents to try to provoke the Germans into hastening an invasion, which he felt sure could be defeated by the Royal Navy and the British Army. This proposal found no favour in Whitehall. Meanwhile the disaster in France had endowed the Wehrmacht with almost magical powers in the minds of the generals, many of whom convinced themselves that Hitler might launch an amphibious assault on Britain with only a few weeks’ preparation, offering no notice to the defenders.