Military history


Resistance and Espionage

‘Now set Europe ablaze’ was Winston Churchill’s instruction to Hugh Dalton on appointing him to direct the Special Operations Executive set up at Churchill’s express wish on 22 July 1940, to foment and sponsor resistance to Hitler’s rule of occupied Europe. No event in the history of occupied Europe’s defiance of Hitler more exactly matched Churchill’s expectation of what a ‘setting ablaze’ might mean than the Warsaw uprising of August 1944. It confronted Hitler with an acute internal military crisis; it threw down a challenge to oppressed peoples elsewhere within his empire to do likewise; it endorsed the message Churchill had proclaimed to the English-speaking nations throughout the war – that the defeated were ready to rise against tyranny when the moment offered; and it validated the ‘parallel’ war of subversion and sabotage sponsored by the British and American ‘special’ agencies inside occupied Europe during four years of conventional war against its periphery.

So it appeared on the surface. Historically, however, it must be recognised that for all the bravery and suffering of the Polish Home Army in seven weeks of combat against Hitler’s security troops – 10,000 fighters killed, perhaps as many as 200,000 civilians killed also – the Warsaw rising was not a spontaneous reaction to the brutality of occupation. Nor, by any objective valuation, did it seriously undermine Hitler’s ability to maintain order within Poland at large while continuing to sustain an effective defence against the Red Army, which had halted on the far side of the Vistula at the moment the rising broke out. On the contrary: the rising was precipitated by the Home Army’s calculation that the Germans’ defeat in the Battle of White Russia presented it with a not to be repeated chance of seizing Poland’s capital city for the government in exile before the arrival of the Red Army led to the installation of Stalin’s puppet Polish regime; but its calculation was invalidated by the failure of the Russians to maintain military pressure on the Germans, who, in turn, found the means to fight – and eventually defeat – the insurgents without drawing on their front-line strength.

Far from demonstrating what an earlier uprising in a series of similar insurrections might have contributed to the defeat of Hitler, therefore, Warsaw stood as an awful warning of how dangerous it was, even at that late stage of the war, for any of his subject peoples to take up arms against him on territory which remained under the Wehrmacht’s control. If Warsaw were not sufficient proof, the point was reinforced by the experience of the Maquis in southern France in June and of the Slovaks in July. In France, on D-Day itself, the Maquis of the Grenoble region set up the standard of revolt on the plateau of Vercors, from which it began to raid German troops using the Rhône valley route; by July there were several thousand Maquisards at Vercors, most of them fugitives from the forced labour programme. Army Group G, which was being troubled by pinprick attacks all over its area of responsibility, then decided to make an example of this isolated and vulnerable resistance base, cordoned the plateau, landed SS troops by glider on the summit and between 18 and 23 July brutally killed everyone they found there. On a small scale it anticipated the action German security troops were simultaneously taking against the Slovak rebels in eastern Czechoslovakia. Elements of the satellite Slovak army rose against the occupation forces in the expectation of imminent Russian intervention, but were not rescued and were put to the sword. Hitler had to deal with no further uprising – except the carefully timed outbreak of insurrection in Paris during the week of its liberation – while his armies still stood on conquered territory.

What made the Vercors massacre all the more dispiriting for those committed to Churchill’s policy of ‘setting Europe ablaze’ was that the resistance had been supported and supplied by the Special Operations Executive; one of SOE’s liaison teams (codenamed ‘Jedburghs’) had been parachuted to the support of the Vercors Maquisards, who on 14 July had received a drop of 1000 loads of weapons and ammunition flown to the plateau by the USAAF. This supply had availed them not at all. Although led by a French regular officer, the resistance fighters wholly lacked the experience and training to engage professional troops – who were in any case indoctrinated to put down resistance with pitiless brutality.

Warsaw, Slovakia and Vercors, coming so late in the course of the Second World War, were key events in the history of Hitler’s Europe against which all other resistance and subversion to his rule between 1939 and 1945 must be set in the balance. (The partisan wars behind German lines in Russia and Yugoslavia are exceptions and require separate consideration.) If the three uprisings typify in their outcome the unintended effect of the programme of subversion, sabotage and resistance which Churchill, later abetted by Roosevelt, and the European governments in exile so ardently supported after June 1940, the programme must be adjudged a costly and misguided failure. All failed at the price of very great suffering to the brave patriots involved but at trifling cost to the German forces that put them down; as a result, all the lesser and preliminary activities of the resistance forces which they crowned must be seen, by any objective reckoning, as irrelevant and pointless acts of bravado. If that is a fair verdict on European resistance and the Allied efforts to plan and support it, what is the explanation for its failure?

At the root of Churchill’s misapprehension of what resistance could achieve against ideological tyranny, a misapprehension shared by hundreds of intelligent and energetic men and women among his fellow countrymen, was a total misunderstanding of the role of public opinion in the politics of conquest. Britain’s history is suffused both by conquest and by resistance to it. In Churchill’s own lifetime the boundaries of the British Empire had been greatly extended by military force, in South, West and East Africa, in the Middle East, in Arabia and in south-east Asia. However, the tide of British imperialism had always been tempered by extraneous factors: the continuing influence of anti-imperialism, domestic and foreign, and the British empire-builders’ own ethos of equity and trusteeship. Confronted by rebellion and atrocity in India during the Great Mutiny of 1857-8, the mid-Victorians reacted with a ruthlessness from which Hitler’s security forces could have learned little. Their successors were raised in a more equitable philosophy of empire. ‘Eventual self-rule’ became the principle on which colonial governments were founded in Africa in the late-Victorian and post-Edwardian era; ‘trusteeship’ was the concept on which Britain administered the African and Arabian mandates granted by the League of Nations; ‘self-rule as soon as possible’ informed the regime which Britain imposed on the Afrikaner republics in the wake of the Boer War; and the same spirit transfused British rule in India in the years after the First World War.

At the heart of Britain’s self-imposed moderation of its right to rule over its enormous twentieth-century empire lay deference to its own democratic beliefs and concern for the good opinion of other peoples, particularly Americans, who shared those beliefs. Churchill, though he had isolated himself from his own party in the 1930s by his opposition to the devolution of government in India, was emotionally, if not intellectually, as committed to the principle of self-determination as the most doctrinaire liberal. Moreover, through his experience in fighting the Afrikaners in the Boer War, he had learned how deep the urge to freedom could drive, and how difficult it was for an occupying power to persist in imposing alien rule on any people inspired by faith in their right to independence. Churchill’s personal experience was reinforced by his wide reading in modern history, which abounded in examples of the success of popular resistance to foreign conquest and domination – for instance, resistance by the Spaniards and Prussians against Napoleon, and by the American colonists against George III.

Hitler’s philosophy of empire

A wider mismatch between the philosophies of empire held by Churchill and Hitler could scarcely be imagined. Imperialistic though he was, Churchill believed in the dignity of man; Hitler held ‘the dignity of man’ to be a bourgeois vacuity. As recognised by those in the Anglo-Saxon world who had read Mein Kampf – they were still only a tiny handful in 1940 – he rejected with contempt the idea of self-rule for those who did not belong to the Germanic race. For purposes of expediency he was prepared to make common cause with the Japanese; out of loyalty he included Mussolini (‘a descendant of the Caesars’) and the Italians in the Germanic confraternity; he had an ideologically soft spot for the modern Greeks, whom he identified with the defenders of Thermopylae against the Asiatic hordes and esteemed as dogged warriors; the Scandinavians he recognised as racial cousins, a title he yearned for the British to accept, and which he also extended to those Dutchmen and Belgian Flemings who identified with his cause; he was prepared at a pinch to include the Finns and Balts among his approved minorities; and, as long as they fought on his side, he excepted the Hungarians, Romanians, Slovaks or Bulgarians from racial stigma. For the rest of the inhabitants of Europe who by the end of 1941 had fallen under his sway he reserved nothing but contempt. They belonged either to those groups, like the French, which were tainted by their subjugation to Roman rule (Hitler’s political memory was long) or to the Slavonic ‘riff-raff’, Poles, Serbs, Czechs and above all Russians, whose history was one of subjection to superior empires.

In consequence Hitler was not at all affected by the moral reservations which so easily touched Anglo-Saxon attitudes to empire. He positively exulted in the ease with which he had extinguished autonomous governments in Poland, Czechoslovakia and Yugoslavia; and he measured the rectitude of the authority with which he had replaced these legitimate regimes purely in terms of expediency: if the successor administrations worked, with the minimum of vexation to his occupying forces, he was content to leave them in office undisturbed. Thus he devolved authority in Norway to the Quisling regime from February 1942 (Vidkun Quisling was the local Nordic authoritarian), conceded continuing rights of parliamentary government to the Danes, who conducted a democratic election as late as 1943, in which 97 per cent of the candidates returned were patriots, and left Pétain to embody the appearance if not the reality of sovereign French head of state even after he had extended German military occupation to the whole of France in November 1942.

The complexity of Hitler’s occupation policies was reflected in the complex pattern of resistance to his occupation regimes in both western and eastern Europe. However, the pattern of resistance was determined not only by the nature of the regime Hitler chose to impose in any particular occupied territory. Three other factors operated: the first was the attitude of the left; the second was the degree of assistance which the British (and, after December 1941, the Americans) were able to bring to local resistance organisations; the third was geography.

Geography, being a constant, is best dealt with first. The degree of success of any movement of resistance to enemy occupation is directly determined by the difficulty of the terrain in which it operates – with this proviso: difficult terrain, mountain, forest, desert or swamp, is bereft of the resources necessary to support an irregular military force, and external supplies are therefore required. Most of German-occupied Europe, however, was either topographically unsuited to irregular operations or too distant from Allied bases of support for irregular forces operating there to be easily and regularly supplied. For example, Denmark, in which the spirit of resistance was strong (despite the existence of military and political groups sympathetic to Hitler’s anti-Bolshevik propaganda), lends itself badly to partisan activity, being flat, treeless and densely inhabited; the same conditions characterise most of Holland, Belgium and northern France. In all those areas clandestine activity was readily monitored by the police – and throughout occupied Europe the domestic police forces accepted the authority and direction of the conqueror from the outset – and reprisal punishments were as readily inflicted. The ease and ruthlessness with which reprisals were carried out, either by the Germans or by their satellite security forces, such as the Vichy Milice, proved a sufficient deterrent for much of the war. Moreover, fear of reprisal – on a scale which ran from curfew through arrest, hostage-taking and transportation to exemplary execution – encouraged informing, which in turn directly heightened the efficiency of German control. Most resistance organisations, when they began to form, were obliged to devote a high proportion of their energy to combating informers, nowhere with complete success.

The only part of occupied western Europe in which the terrain favoured resistance activity was Norway, north of Oslo; but there the population was so sparse and the density of German occupation troops was so high that all guerrilla activity had to be organised outside the country. The infiltration of Norwegian resistance fighters from Scotland (who in February 1943 destroyed the heavy-water plant at Vermork, thus crippling the German atomic weapons programme), reinforced by the programme of British commando raids against German military outstations, had the highly desirable effect of persuading Hitler grossly to over-garrison Norway throughout the war; but the internal resistance itself was of negligible strategic significance.

Certain regions of eastern and south-eastern Europe were topographically favourable to partisan activity, notably Carpathian Poland, the Bohemian Forest in Czechoslovakia, much of Yugoslavia, the mountainous parts of the Greek mainland and its larger islands, and the Italian Alps and Apennines. The growth of resistance in Italy, however, had to await the fall of Mussolini in July 1943, while Czechoslovakia was too distant from bases of external support for resistance to take root. The Czech government in exile ran the most efficient of Allied-oriented intelligence organisations to operate inside Europe during the war, but SOE’s only serious sponsorship of resistance activity inside the country, the assassination of Reinhard Heydrich, SS ‘Deputy Protector of Bohemia-Moravia’, in May 1942, provoked so terrible a reprisal (the extinction of the population of the village of Lidice) that the effort was not repeated; it reveals much about the efficiency of Hitler’s occupation policies that the assassins were betrayed by one of their own number, who made himself known to the Gestapo as soon as he was parachuted into his homeland. In Greece, where SOE set up an extensive network of agents as early as the autumn of 1942, many of them Oxford- and Cambridge-educated classical scholars inspired by the philhellenes (Byron foremost among them) who had aided the Greeks in their struggle against the Turks in the 1820s, the Germans responded to partisan activity with such pitiless cruelty that the British officers soon found themselves obliged actually to dissuade activists from initiating attacks against the occupiers.

In Poland – again partitioned after 1939 so that its western province became German, its eastern Russian and only its centre, the ‘General-Government’, remained a separately administered entity – the ‘Home Army’, under the direction of the government in exile in London, abstained from provocative military action against the occupier until it unleashed the Warsaw rising of August 1944. Though the Poles ran an intelligence network second in efficiency only to that of the Czechs (one of its triumphs was to supply the British government with key parts of crashed German pilotless weapons which had made rogue flights), they decided from the outset that the national interest lay in preserving the strength of the Home Army against the moment when the collapse of Germany would allow it to strike for the recovery of independence. The military efforts of the Home Army were also restricted, however, by its difficulty in acquiring arms. Its lack of weapons was a factor in its nonintervention against the Germans during their destruction of the Warsaw ghetto in April 1943, when its heroic Jewish resistance groups were systematically overwhelmed in a street-by-street battle conducted by SS troops and militia under the command of SS General Jürgen Stroop. Until 1944 SOE lacked aircraft with sufficient range to reach central Poland; even after the acquisition of bases in Italy in 1943, flights were still lengthy and dangerous. The Soviet Union, which occasionally granted the Western air forces refuelling facilities for bombing raids against Germany, refused to do so for arms-dropping missions to Poland. It also refused to supply arms to the Home Army itself.

Russia’s attitude was determined by its political differences with the government in exile and the Home Army, which persisted even after the signing of the agreement in August 1941 which released Polish prisoners held in Russia to join the British armies in the Middle East. Stalin had politically identified the Home Army as a potential opponent of the Polish Communist Party, through which he began to sponsor his own army in exile in the Soviet Union after June 1941. This was the only negative effect of Barbarossa on the development of resistance to German occupation inside Hitler’s Europe. Almost everywhere else the efforts were positive. The European communist parties, through the persisting control of the Comintern, had been restrained from joining in resistance to occupation as long as the Molotov-Ribbentrop Pact remained in force. As soon as it was broken, all European communist parties were ordered to initiate subversive activity, with a marked increase in the efficiency of resistance groups of whatever political colour. This effect was due either to collaboration by the communists, whose habits of secrecy were far superior to those of recently formed clandestine groups, with the non-communist resistance, as notably in Holland, or to creative competition between left and right, as in France: there de Gaulle, alarmed by the prospect that ‘Free France’ might fall under communist leadership on home territory, succeeded in creating a pan-resistance ‘Secret Army’, commanded by a National Resistance Council under his authority. The marriage it imposed between communist and non-communist groups was one of convenience. The French Communist Party privately reserved the intention to operate to its own political advantage as soon as opportunity offered, and it did indeed institute local reigns of terror against its committed opponents during the interregnum which followed liberation in August 1944; but from June 1941 to July 1944 the marriage worked to unify and strengthen the resistance as a whole.

Objectively, however, it must be recognised that the principal achievement of resistance in western Europe during the years of Hitler’s strength was psychological rather than material. The most visible symbol of resistance was the underground newspaper (120 separate imprints were circulating in Holland in 1941) and the most seditious activity the transmission of intelligence, of varied value, via clandestine networks to London. Some of these networks fell into enemy hands and were ‘turned’; the North Pole network, for example, was ‘run’ by the Germans between March 1942 and April 1944. Such setbacks did little harm to the Allied war effort but resulted in numbers of brave men and women (SOE judged that women made better agents than men) being parachuted straight into the hands of the Gestapo. The publication of underground newspapers and the running of intelligence networks, whose subsidiary activities included the smuggling of crashed aircrew out of occupied territory, occasional acts of sabotage and sporadic assassinations, did a great deal to sustain national pride during the occupation years, but none of the activities shook the German system of control, which was both efficient and remarkably economic. Historians of the resistance are naturally reluctant to put figures to the size of the German security forces (civilian Sicherheitsdienst, military Feldgendarmerie) which were the resistance groups’ enemies, but it is probable that their total strength in France did not exceed 6500 at any stage during the war; the German police garrison of Lyon, the second largest city of France, comprised about 100 secret policemen and 400 security troops in 1943. The divisions of the German army stationed in France (sixty in June 1944) took no part whatsoever in security duties, and, since they were almost exclusively stationed in coastal districts, they were not in a position to do so. Against the German security forces the resistance deployed at most 116,000 armed men, a figure established in July 1944 when the arrival of the Allied liberation armies raised their strength to its maximum. During the occupation proper, the number and size of armed groups were small and their activities consonantly limited; in the first nine months of 1942 the total number of assassinations of German security officers was 150, while major acts of sabotage throughout the war did not exceed five (interference with the railway network was extensive, but was largely confined to the months before and during the D-Day landings).

The popular idea of western Europe ‘ablaze’ under German occupation, first promulgated in John Steinbeck’s inspirational novel The Moon is Down (1942) and fed by an army of authors since, must therefore be recognised as a romantic, if understandable, myth. Western Europe’s urban and pastoral regions, where the population was so vulnerable to reprisals, were quite unsuited to the sort of sustained partisan activity which, when supplied and supported by external regular forces, is the only form of guerrilla warfare which constrains a conqueror to divert appreciable military effort from the battlefront. During the whole course of Hitler’s war, he was confronted with such effective guerrilla resistance in only two areas of operations: in the rear of the Eastern Front, where Stalin, after an initial hesitation, supported, supplied and eventually reinforced partisan formations centred on the impenetrable Pripet Marshes; and in Yugoslavia.

The Soviet partisan formations were initially based on fragments of regular divisions isolated by the German advance through White Russia and the Ukraine in the summer of 1941, survivors who retained the will and some of the means to fight on after they had been cut off from their higher headquarters and sources of supply. For recruitment, however, they depended upon volunteers from the White Russian and Ukrainian populations, both suspect in Stalin’s eyes as undependable minorities and as potential collaborators with the occupation authorities. From the outset he put the partisan formations under NKVD (secret police) control; the command structures, infiltrated through German lines to the partisan bands, were known as orgtroika (tripartite organisations) consisting of state, party and NKVD officers. As late as the summer of 1943, their members in the Ukraine did not exceed 17,000. In January 1944, when the partisans were returned to Red Army control, thirteen partisan brigades in the Ukraine numbered 35,000; on the eve of Operation Bagration in June 1944, when partisans carried out 40,000 railway demolitions, their numbers were 140,000. They had grown as a result of Soviet support, despite ferocious German repression. From the spring of 1944 onwards, specialist SS anti-partisan units, to which German formations ‘resting’ from operations at the front were regularly attached, carried out sweeps through ‘band-infested’ areas, burning and killing without pity; ‘kills’ of up to 2000, including women and children as well as men, were regularly reported for each operation. Post-war investigations by historians with access to German records suggest that such sweeps were extremely effective, that Soviet estimates of the achievements of partisans were wildly exaggerated, and that the losses inflicted by partisans, whether on the personnel or the material of the Wehrmacht, were a fraction of those claimed by the Soviet authorities. The Soviet estimate that 147,835 German soldiers were killed by partisans in the Orel region, west of the River Don, has been challenged by a Western scholar, J. A. Armstrong, who suggests a figure of 35,000 killed and wounded.

The Yugoslavian Partisans

It is to Yugoslavia that historians ultimately turn in arguing for the effectiveness of partisan warfare and in estimating the contribution of resistance forces to the defeat of the Wehrmacht in Europe in the Second World War. Yugoslavia is unquestionably a special case. Its mountainous terrain, intersected by deep valleys and bounded by a coastline that gave easy access to SOE’s air and sea supply units, is ideally suited to irregular warfare. Its Serbian population was accustomed by resistance to the Turks and by the Austrian invasion of 1914-15 to fighting on its home territory. Hitler’s aggression of April 1941 had outraged the national pride and by its suddenness left hundreds of military units in possession of weapons and ground which provided the basis for irregular operations. The first to raise the standard of revolt were Serbian monarchists commanded by a Serbian regular officer, Draza Mihailović. His Chetniks, so called from the Serbian word for opponents of the Turkish occupation, were at odds from the outset with the Croatian Ustashi who made common cause with the Italian occupation forces in Slovenia and Croatia; they also understandably opposed the Hungarian, Bulgarian and Albanian appropriations of Yugoslav border areas on the northern and eastern frontiers of the kingdom. Properly, however, their quarrel was with the Germans, who had imposed a puppet government on the territory of historic Serbia and against whom they initiated partisan warfare as early as May 1941.

The Special Operations Executive made contact with the Chetniks in September 1941 and began to supply them with weapons and money in the summer of 1942. However, SOE’s original emissary to Mihailović, Captain D. T. Hudson, had also come across groups of anti-monarchist guerrillas who called themselves ‘Partisans’ and were led by an experienced Comintern agent, Josip Broz who used the nom de guerre Tito. Hudson early formed the impression that Tito was a more serious opponent of the Axis occupiers than Mihailovicü, whom he suspected of wishing to build the Chetniks into a Serbian ‘Home Army’ on the Polish model and preserve its strength against the day when external circumstances would allow him to liberate the country from within. His suspicion did Mihailović less than justice, for the Chetniks were conducting a guerrilla war against the Germans in 1942 and (as Ultra revealed) were regarded by them as troublesome enemies as late as 1943. It was undoubtedly the case, however, that Mihailović was an extreme Serb nationalist, that he refused to co-operate with Tito in creating a national resistance movement, that his Chetniks had begun to fight the Partisans for control of western Serbia in November 1941, and that he early entered into local truces with the Italians to acquire arms for the prosecution of this burgeoning civil war.

A principal motive of Mihailović’s policy was to spare the Serb population from reprisal and atrocity at the hands of the occupiers – an estimable aim in view of the appalling consequences of the internal war which none the less ensued, costing as it did the lives of nearly 10 per cent (1,400,000) of the pre-war population. Tito made no such reservations. In the classic tradition of revolution, he committed the Partisans to waging war against the occupier to the bitter end. By late 1943 he had established himself in the eyes of SOE (whose Yugoslav section was dominated by officers with left-wing views) as the most effective of the Yugoslav guerrilla leaders. From the spring of 1944 onwards all British aid was sent to Tito’s Partisans and withdrawn from Mihailovicü. Although some officers of the American Office of Strategic Services remained in contact with the Chetniks, their abandonment by the British had the effect of driving them into closer co-operation with the Germans, with whom Mihailović agreed to a local armistice in November 1943 as a means of continuing the civil war against Tito, thus confirming the Allied prejudice against them which Hudson had voiced at the outset.

Tito meanwhile had been building up his army and instituting increasingly ambitious attacks against the Germans in central and southern Yugoslavia. When these attacks began to threaten the Germans’ exploitation of the country’s mineral resources and their line of communication with Greece, Hitler was forced to commit sizeable forces and mount large-scale pacification operations against them. Until the collapse of Italy in September 1943 twenty Italian divisions were permanently stationed in Yugoslavia and Albania (where SOE also sponsored a minor guerrilla movement), together with six German divisions. After the dissolution of the Italian occupying force, the German was reinforced with an additional seven divisions, together with four from the Bulgarian army. A Partisan offensive at the Neretva river in Bosnia in February 1943, defeated at some cost to the Italians and Germans, prompted them to launch Operation Schwarz in the following May. It involved over 100,000 German and satellite troops and drove Tito out of Montenegro, where he had retreated. Similar offensives cleared western Bosnia in December, while in May 1944 Operation Knight’s Move in southern Bosnia was so successful that Tito was obliged to seek rescue at British hands and fly to Bari in Italy – even though at the time of the September armistice he had acquired large quantities of Italian weapons which allowed him to raise the number of armed men he kept in the field to about 120,000.

The Royal Navy quickly returned Tito to Yugoslavia, though only as far as the island of Vis, where it had established a base to support Partisan operations. Meanwhile the British Balkan Air Force, set up at Bari in June, was flying vast quantities of (largely American) weapons to the Partisans in the interior of the country. In August Tito left Vis to visit Stalin, who until February 1944 had been tepid in his support for Tito’s campaign; in Moscow Tito granted ‘permission’ for Soviet troops to enter the country and they began to cross the border from Romania on 6 September. Their arrival, and Hitler’s decision to evacuate Greece in October, transformed the Partisans’ position. Army Group F, outflanked in the Balkans by the Red Army and along the Adriatic coast by Allied Armies Italy, immediately beat a hasty retreat into central Yugoslavia. Belgrade, the capital, fell to a joint force of the Red Army and the Partisans on 20 October. Stalin, at his August meeting with Tito in Moscow, had given a guarantee that the Red Army would evacuate Yugoslavia as soon as its presence was no longer militarily necessary, and his promise was indeed kept after the German surrender of May 1945.

Mihailović ended the war a tragic figure. Tito’s ascendancy had driven him deeper into complicity with the Germans; his belated efforts to reingratiate himself with the Allies totally failed, and after having hidden from Tito’s troops in the mountains of central Serbia for over a year he was caught in March 1946, tried in Belgrade in June and executed by firing squad on 17 July. His plea of exculpation, ‘I wanted much, I began much, but the gale of the world swept away me and my work’, has entered into the memorabilia of the Second World War. ‘Destiny’, he said, had been ‘merciless’ to him, and hindsight, by which many of his judgements have been forgiven, accords weight to that view. His tragedy was to have been a nationalist leader in a state composed of minorities, whose differences Hitler cynically exploited in order to divide and rule.

Hindsight has also greatly diminished Tito’s achievement. At the end of the war he was widely hailed as the only European resistance leader to have liberated his country by guerrilla effort. Many strategic commentators further credited him with having diverted such numbers of German and satellite troops from the eastern and Mediterranean battlefields as to have materially influenced the outcome of the war in those theatres. Realistically, it is now accepted that the liberation of Yugoslavia was the direct result of the arrival of Russian troops in the country in September 1944. What now seems most surprising about the Tito era is that Stalin should have so unwisely agreed to remove the Red Army from Yugoslav territory at the moment of victory – a misjudgement which robbed Soviet post-war control of eastern Europe of consistency from the outset. Strategically, estimates of Tito’s diversion of force from Hitler’s main centres of operation are now seen to be exaggerated. The principal army of occupation in Yugoslavia was always Italian. After the Italian collapse Hitler was indeed obliged to double the number of German divisions deployed in Yugoslavia from six to thirteen; but few were suitable for use against the Red Army or Allied Armies Italy. Only one, the 1st Mountain Division, brought from Russia in the spring of 1943, was first class; the rest, including the SS Prinz Eugen and Handschar Divisions and the 104th, 117th and 118th Divisions, were composed either of ethnic Germans from central Europe or of locally enlisted non-German minorities, including a high proportion of Balkan Muslims from Bosnia and Albania. They were quite unsuitable for war against Russian, British or American mechanised formations; their presence in Yugoslavia, even their existence, was in itself evidence that fighting there partook more closely of the character of civil rather than international war. In a sense, Hitler’s cunning in setting Serb against Croat and monarchist against communist rebounded on itself; for, though his only real interest in the country lay in the exploitation of its resources and the free use of its lines of communication to southern Europe, he eventually became a party to its internal quarrels. In objective military terms, his involvement cost him little, but it would have simplified his politico-military arrangements if he had taken the trouble, after his whirlwind victory of April 1941, to establish a pan-Yugoslav satellite administration, charged with maintaining order within the country, rather than cynically bribing Yugoslavia’s neighbours with portions of its territory to impose occupation policies which rapidly proved ineffectual.

The Special Operations Executive, though puffed by a powerful lobby of historians, some of whom were its former officers, largely fails in its claim to have contributed significantly to Hitler’s defeat, since its achievement in Yugoslavia, its principal theatre of operations, was ambiguous. The same verdict holds true for the activities of the American Office of Strategic Services (OSS), set up in June 1942. Through an agreement allocating responsibilities between OSS and SOE signed on 26 June 1942, OSS took the major role in supporting the Italian partisans and the Johnny-come-lately resistance movements in Hungary, Romania and Bulgaria. Italian resistance activity discommoded the Germans very little, the Hungarian, Romanian and Bulgarian subversives scarcely at all. SOE’s and OSS’s parallel effort in psychological warfare (sponsored in Britain by SOE’s parent organisation, the Ministry of Economic Warfare, through its Political Warfare Executive) afforded high excitement to the journalists and intellectuals who staffed it; its effect on opinion in the occupied countries was marginal and on German civilian morale negligible. ‘Black propaganda’, transmitted by radio stations purporting to operate within the boundaries of the Reich, understandably convinced no German who could daily witness the absolute control the Gestapo exercised over German society. The only non-military manifestation of internal resistance to Nazi rule, the Catholic Bavarian White Rose group, was pitilessly liquidated almost as soon as it appeared in February 1943. Allied efforts at economic warfare were equally unavailing; the principal success, the purchase of future production of Swedish ball-bearings, was negotiated so late in the war (mid-1944) that victory had been won by conventional military means before it could take effect.

The ‘indirect’ offensive encouraged and sustained by the Allies against Hitler – military assistance to partisans, sabotage and subversion – must therefore be judged to have contributed materially little to his defeat. Among his army of 300 divisions deployed across Europe on 6 June 1944, the last moment in the war when Hitler exercised unchallenged control over the greater part of the territory he had conquered in 1939-41, fewer than twenty can be identified as committed to internal security duty. Outside central Yugoslavia, parts of western Russia far behind the Wehrmacht’s lines and tiny pockets of defiance in mountain Greece, Albania and southern France, all peripheral to his conduct of the larger war, occupied Europe lay inert under the jackboot. The ‘dawn of liberation’, so seductively promised by Churchill, Roosevelt and the governments in exile to the conquered populations, was signalled only by the flicker of gunfire at the military boundaries of the Wehrmacht’s zone of operations.

The bacillus of espionage

If the structure of Hitler’s empire was penetrated and fissured by clandestine activity, that took a form quite different from the ‘setting ablaze’ Churchill had so optimistically demanded in July 1940. Resistance may have been a gnat on the hide of the Wehrmacht; espionage was a bacillus debilitating its vital system. The real triumph of the Allies’ indirect campaign against Hitler between 1939 and 1945 was won not by the brave and often foolhardy saboteur or guerrilla warrior but by the anonymous spy and the chairborne cryptographer.

Of the two, spies were by far the less important. Popular imagination invests ‘Humint’ (human intelligence, in the jargon of the trade) with a significance even greater than it gives to the resistance fighter; certainly far greater than is given to ‘Sigint’ (signals intelligence). Moreover, governments to a considerable degree conform to popular estimations of the worth of a spy. The notion that the inner councils of the enemy are penetrated by an ‘agent in place’ who transmits their deliberations and decisions swiftly and directly to his master in the friendly camp is beguilingly attractive to any war leader; Churchill, Roosevelt, Stalin and Hitler were all beguiled in this way during the Second World War. Hitler, for example, was led to believe by the Wehrmacht intelligence service, the Abwehr, that it maintained an extensive network of agents in Britain who were able to report after June 1944 on the accuracy of pilotless-weapons strikes on London. Churchill and later Roosevelt were supplied through the Czech intelligence service with significant information of German capabilities and intentions by Agent A-54, probably the Abwehr officer Paul Thümmel. Stalin, who benefited from the dedication of the international communist movement’s members to the Soviet cause, drew on the Swiss-based ‘Lucy ring’ for information of German activities in occupied Europe, on Richard Sorge’s network in Japan for warning of German military intentions, on the ‘Red Orchestra’ for day-by-day intelligence of the German order of battle and, during 1941-2, on the Schulze-Boysen Luftwaffe network (a Red Orchestra component) for technical data; through the ‘Cambridge Comintern’, composed of British intelligence officers, Anthony Blunt, Guy Burgess and Kim Philby, Stalin also kept his finger intermittently on the pulse of Anglo-American higher strategy.

All these sources were, however, to some degree unsatisfactory or compromised. Agent A-54’s transmissions, for example, were too sporadic to provide a coherent picture of German strategy. The Red Orchestra was wrongly placed to monitor key German military activity, the Schulze-Boysen network was insecure and quickly penetrated (117 of its members were hanged), Sorge was too detached from the Comintern network to be always believed (though he undoubtedly influenced Stalin’s decision to transfer troops from Siberia to Moscow in the winter of 1941), while the Lucy ring was probably transmitting information tailored and supplemented by the Swiss intelligence service for its own purposes; another interpretation is that the Lucy ring derived its information from Bletchley, either directly or through Allied agents in Swiss intelligence. The Cambridge Comintern was perhaps the most influential of all Stalin’s networks, though in a reverse direction; Philby, by deliberately maligning his circle’s reliability, may have been decisive in dissuading the British government from lending support to Stauffenberg’s anti-Hitler conspiracy, which Stalin undoubtedly judged inimical to his long-term plans for the post-war control of Germany, since the conspirators were avowedly anti-communist. Least satisfactory of all the networks was the Abwehr’s in Britain; it was turned as early as 1939 by the capture of one of its spies, and after that all the information it transmitted to Germany was compiled by the British officers of the ‘Double Cross’ organisation which controlled subsequently captured agents. One of the controllers’ achievements was to persuade the German staff of the pilotless-weapons force progressively to shorten the range of their launched missiles, so that the majority fell south of London.

The role of Ultra

The contribution of ‘Humint’ to the direction of strategy in the Second World War looks all the more marginal and patchy when compared with that of ‘Sigint’. Signals intelligence is concerned with the interception, decryption and interpretation of the enemy’s secure messages, however transmitted, and the protection of one’s own from his interception services. In practice the majority of material so intercepted in the Second World War was radio traffic protected by elaborate mathematical ciphers, though some traffic was sent by the older system of codes, constructed from secret codebooks; much tactical intelligence, known to the British as ‘Y’, was gleaned from messages sent in ‘low-grade’ ciphers or even en clair (not in cipher) between units in the heat of the action.

All five major combatants, Germany, Britain, the United States, the Soviet Union and Japan, devoted costly and extensive efforts to protecting their radio signals traffic and seeking to penetrate that of the enemy (telex, telegraph and telephone traffic sent along landlines – which carried, for example, 71 per cent of all German naval traffic in 1943 – proved generally impenetrable, but had limited use). Minor combatants, notably the Poles, French and Italians (whose codes and ciphers were exceptionally secure), also played a major role in the radio warfare. In particular it was the Poles’ early success in attacking Germany’s military machine cipher (Enigma), subsequently revealed to the French, which eventually allowed the British to break Enigma on a regular and rapid basis, thus laying the foundations for the Ultra organisation, which disclosed information of truly war-winning value to the Allies from late 1940 onwards.

The extent of the Ultra triumph is now so well known (the equally important American ‘Magic’ penetration of the Japanese naval and diplomatic ciphers less so) that consideration of both ought to wait upon an evaluation of the cryptographic successes of other combatants, which were more significant than received opinion admits. It is probable, for example, that the Russians had their own success against Enigma; so Professor Harvey Hinsley, the historian of Ultra, guardedly indicates. Russia’s own high-grade ciphers were certainly of the best quality, and this suggests a capacity to read others; they had not yielded to foreign intelligence services’ attack for some years before 1941 (Churchill forbade the British Government Code and Cipher School from making the attempt after 22 June 1941). Russian medium- and low-grade ciphers, however, were much read by the Germans in 1941-2 and perhaps later; the decrypts yielded valuable tactical intelligence. The Germans also succeeded in breaking the American military-attaché code in late 1941, and their decrypts of messages originating with the US liaison officer in Cairo supplied Rommel with important information about the Eighth Army in the desert.

The most important German success, however, was in breaking the British naval book ciphers, to which the Admiralty clung long after the army and air force had gone over to more secure ciphers. These ciphers (nos. 1, 2, 3 and 4) were more properly book codes: the letters of a message were translated into figures by reference to standard tables and then ‘super-enciphered’ by mathematical techniques, which were altered at regular intervals. The weakness of the system was that the book itself might be reconstructed if sufficient radio traffic was collected and analysed by the enemy, who could then apply normal calculations of mathematical probability to break the super-encipherment. This was exactly the achievement of the German navy’s Observation Service (Beobachtungs- orB-Dienst); by April 1940 it was reading 30-50 per cent of traffic encoded in naval cipher no. 1; when a change was made to cipher no. 2 it again broke this traffic on a large scale between September 1941 and January 1942; it had less success with the replacement, no. 4; but between February 1942 and June 1943, with short interruptions, it was reading as much as 80 per cent of no. 3, often in ‘real time’. ‘Real time’, a cryptographer’s term, means that messages sent are intercepted and broken by the enemy at the same speed as they are received and decrypted (or decoded) at the denominated station. What made the B-Dienst’s success against naval cipher no. 3 so disastrous for the Allies was that it was the code used to carry information between London and Washington about transatlantic convoys; as a result the B-Dienst ‘was sometimes obtaining decrypts about convoy movements between 10 and 20 hours in advance’ of their departure, according to Harold Hinsley. Such information was the key to the success of Dönitz’s U-boat wolf packs, which, alerted by such intelligence, could be deployed across the track of an east- or west-bound convoy in numbers that frequently overwhelmed their escorts. It was not until the Admiralty accepted a combined cipher machine (CCM), employed also by the American and Canadian navies and brought into general use in 1943, that the German navy’s penetration of convoy ciphers in the Battle of the Atlantic was ended. By then, however, the balance of advantage in the battle had been shifted to the Allies by conventional military means.

In the land and air war, the Allied armies and air forces conceded no such advantage to the enemy as the British Admiralty did by its arrogant persistence in the use of book codes; they used machine cipher systems from the outset and in consequence resisted German attack on their secure transmissions. The German services were also committed to a machine cipher system, but, having adopted theirs ten years before the British and Americans, found themselves – unwittingly – at the outbreak of the war equipped with a semi-obsolete system. Hence the success of the British Government Code and Cipher School (GCCS), located at Bletchley, between Oxford and Cambridge (from which it drew so much of its talent), at breaking into the transmissions encrypted on the Enigma machine the Germans used.

The Enigma machine outwardly resembled a portable typewriter but the depression of a key worked an internal system of gears which allotted any letter input an alternative letter not logically to be repeated before 200 trillion subsequent depressions. The Germans therefore understandably regarded Enigma transmissions as unbreakable in ‘real time’, indeed in any sort of human time whatsoever. Unfortunately for them they were deceived; because of the need to indicate to a receiving station the way in which the sending Enigma machine had been geared to transmit, the operator was obliged to preface each message with a repeated sequence of the same letters. This established a pattern which a trained mathematician could use as a ‘break’ into the message and so into the whole of its meaning. As the mathematicians recruited by Bletchley included Alan Turing, the author of universal computing theory, Gordon Welchman, a principal pioneer of operational analysis, and Max Norman and Thomas Flowers, designer and builder respectively of the first electronic computer (‘Colossus’, so called at Bletchley because of its enormous size), such ‘breaks’ were rapidly exploited to yield complete readings of German messages quite quickly after interception – and eventually in ‘real time’.

There were important exceptions to Bletchley’s success. Luftwaffe ‘keys’ – the different methods of enciphering Enigma traffic used by separate German service branches – proved easier to break than army and naval keys, and some naval keys were never broken; significantly, nor was the Gestapo key, though it was not changed from 1939 until the end of the war. Enigma security depended heavily upon the experience and skill of the German senders; mistakes in procedure made by inexperienced, tired or lazy operators provided Bletchley with the majority of their ‘breaks’ into traffic. Gestapo operators were meticulous; so too were the naval officers who used the ‘Shark’ key controlling U-boats in the North Atlantic. For most of 1942, while the B-Dienst was regularly reading naval cipher no. 3 in real time, Shark resisted all Bletchley’s efforts; during those months (February-December) the Germans were masters of the radio war in the Battle of the Atlantic. In consequence hundreds of thousands of tons of Allied shipping were sunk.

The Shark episode was, however, an exception to the general rule that the British dominated radio warfare in the West, as the Americans did in the Pacific, where they matched Bletchley’s achievement by breaking both the Japanese naval (JN 25b) and diplomatic (Purple) machine ciphers before the outbreak of the war. The joint Allied triumph, successfully concealed from both enemies throughout the war, naturally prompts the query why, if the Allies enjoyed such direct access to the most secret internal messages sent by their opponents, they were nevertheless on occasion suprised by large-scale enemy initiatives – Pearl Harbor, Crete and the Ardennes offensive being the obvious examples. The answer is that there are limits to the usefulness of even the best intelligence system, and this is precisely demonstrated in different forms by each of these episodes. The Japanese, for example, disguised their intentions before Pearl Harbor by hiding their fleet in the remoteness of the Pacific and imposing absolute radio silence on its units, which moved to their attack positions by preordained plan; alert though the Americans were, they were thereby denied the intelligence which would have allowed them to anticipate attack. Before the Ardennes the Germans also imposed radio silence on their attack units. Nevertheless, primarily through troop movements, they unwittingly betrayed sufficient warning to the Allies of the attack they planned for a truly sensitive intelligence organisation to have detected the danger and alerted higher authority. Both the intelligence service and higher headquarters had, however, persuaded themselves that the Germans were too weak to launch an offensive on the Ardennes front during December 1944; accordingly they discounted the evidence to the contrary and so were discountenanced.

The case of Crete reveals a third and highly frustrating limitation in the use of intelligence: the inability to act on clear warning because of disabling weakness. Before the German parachute landings in May 1941, Ultra – the organisation which evaluated and distributed the raw decrypts produced by Bletchley – had identified from Enigma intercepts both the German order of battle and the German plan. However, Freyberg, the British commander on the island, lacked not only the troops but also (more ironically) the transport that would have enabled him to concentrate counter-attack forces swiftly against points of danger. As a result the Germans, despite heavy initial losses, seized a vital airfield which allowed them to fly in reinforcements and swamp the defences.

There is a fourth and universal limitation on the usefulness of intelligence: the need to protect a source. It has been widely alleged, for example, that Churchill ‘allowed’ Coventry to be bombed in November 1940 because to have taken extraordinary defensive measures against the attack would have revealed to the Germans the ‘Ultra secret’. It is now known that this interpretation is false; although Churchill did indeed have advance warning via Ultra of the Coventry raid, it was too short to enable defensive measures to be taken – which he would certainly have done, at whatever the risk of compromising Ultra, had time been available. A more telling accusation is that in the weeks before Barbarossa the British did not validate their warnings to the Russians of the imminence of the German attack by revealing the authenticity of the source. However, in view of Stalin’s wishful thinking to the contrary and his desire to placate Hitler at any cost, the betrayal to him of the Ultra secret would have plumbed the depths of insecurity. In this case, as in every other where such a calculation had to be made, Churchill was unquestionably right to put the long-term security of the source above current advantage.

Despite the intrinsic and artificial limitations to the usefulness of Allied access to the enemy’s secret traffic, both Ultra and the American ‘Magic’ organisation were undoubtedly responsible for major, even crucial, strategic success in the Second World War. The first and most important was the victory of Midway, where knowledge of Japanese intentions allowed the Americans to position their inferior fleet of carriers in such a way as to destroy the much larger enemy force. Midway, the most important naval battle of the Second World War, reversed the tide of advantage in the Pacific and laid the basis for America’s eventual triumph. In the European theatre, Ultra supplied Montgomery with vital intelligence of Rommel’s strength and intentions both before and during the battle of Alamein and later provided Alexander in Italy with timely warnings of the German intention to counter-attack at the Anzio bridgehead – ‘one of the most valuable decrypts of the whole war’, according to Ralph Bennett in his account of the role of Ultra in the Mediterranean. Ultra intelligence also allowed Alexander correctly to time his subsequent break-out from Anzio and enabled General Jacob Devers to undertake his headlong pursuit of Army Group G up the Rhône valley after the landing in Provence in August 1944, safe in the knowledge that this would not be opposed.

Ultra’s greatest contribution to the war in the West, however, occurred during the Battle of Normandy, when Bletchley provided Montgomery with information of day-to-day German strengths at the battlefront, of the effect of Allied air-strikes, such as that which destroyed the headquarters of Panzer Group West on 10 June, and eventually of Hitler’s order to counter-attack at Mortain against the flank of Patton’s break-out into Brittany – a disclosure which led to the destruction of Army Group B’s armoured reserve and to the climactic encirclement of the Westheer in the Falaise pocket. The Mortain decrypts were certainly the most important which came to any general on any front throughout the course of the Second World War.

Whether Ultra ‘shortened the war’, as is sometimes suggested, or even materially altered its course, is more difficult to argue. There was no single Ultra triumph as great as the American codebreakers’ success in identifying Midway as the target for the Japanese fleet in June 1942, a genuinely tide-turning intelligence operation. Although the breaking of the Shark key in December 1942 very greatly contributed to the winning of the Battle of the Atlantic in the following spring, against it must be set the cost of the B-Dienst’s concurrent success in reading the British naval convoy codes. Ultra did not much influence the course of the war in the air, despite the insecurity of the Luftwaffe keys, and in the ground fighting between the Germans and the Western Allies it can never be said to have given the advantage consistently to the eavesdropping side. That was because, as Clausewitz’s famous and accurate observation on combat reminds us, on the battlefield ‘friction’ always intervenes between the intentions and achievements of even the best-informed general: accident, misunderstanding, delay, disobedience inevitably distort an enemy’s plans so that, whatever advance knowledge his opponent may have of them, he can never so predisposition his troops and responses as to be sure of frustrating the enemy’s actions; nor, because of ‘frictions’ working against him, can he count on smoothly carrying out his own counter-measures. Ultra reduced friction for the Allied generals; but it did not abolish it.

If we shift the focus and ask whether in the spectrum of clandestine warfare cryptanalysis was more or less valuable to the Allies than the activity of the resistance, the answer is simple. Cryptanalysis was consistently and immensely more valuable indeed. The Second World War in the West could have been won without either the resistance or Ultra; but the cost of the former was heavy, and its material, as opposed to psychological significance was slight. The cost of Ultra, by contrast, was trivial – the whole apparatus employed only 10,000 people, including clerks and cryptographers – while its material value was considerable and its psychological significance inestimable. The proof of that comes from the German as well as the Allied side. Ultra sustained the confidence of the very few Western decision-makers who were privy to its secret in a way nothing else could have done. Twenty years after the war was over, when their German opponents discovered that their most secret correspondence had been read daily by the British and Americans, they were struck speechless.

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