Interwar policy and the disaster at Dunkirk, 1940

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Outgeneralled, the British Army crashed to defeat before the German Blitzkrieg in May 1940. The greatest defeat in British imperial history, it was the price of interwar conservatism. But the soldiers had fought with gritty determination and most of them were rescued from the beaches of Dunkirk. So Britain would survive to fight again.

The Battle of Dunkirk lasted from 24 May to 4 June 1940.

‘The English soldier was in excellent physical condition. He bore his own wounds with stoical calm. The losses of his troops he discussed with complete equanimity. He did not complain of hardships. In battle he was tough and dogged. His conviction that England would conquer in the end was unshakeable…’.

This opinion was enshrined in an official military report of the German IV Corps, Sixth Army, discussing operations in north-west Europe during May 1940. It continued: ‘The English soldier has always shown himself to be a fighter of high value. Certainly the Territorial divisions are inferior to the Regular troops in training, but where morale is concerned they are their equal.

‘In defence the Englishman took any punishment that came his way. During the fighting, IV Corps took relatively fewer English prisoners than in engagements with the French or Belgians. On the other hand, casualties on both sides were high.’

Something had clearly survived of the centuries-old British military tradition. It was rooted in the militia service of  ‘the middling sort’ in the Middle Ages, and it had given rise to a distinctive ‘British way of war’ embodied in the practice of the New Model Army, in the victories of Marlborough’s and Wellington’s redcoats, and in the steady, massed, precision musketry at Mons in 1914. At times the thread of tradition had worn perilously thin, but something always survived – the British at war continued to be an army of free men, fighting defensively in line, each man supporting his mates on either side, in the manner of King Harold’s fyrd on Senlac Hill.

That this was so became increasingly apparent as the disaster of May 1940 unfolded. The British Army might have fallen apart. Much of the French Army did so (though not all) once it was clear that the Germans had broken the line and surrounded the main masse de manoeuvre of the Allied forces in Belgium. But it did not. Instead, British commanders thought on their feet, acted fast, and improvised hasty defensive lines out of almost nothing, while the men on the ground dug in when ordered and fought on with grim resolution in a battle of a kind that none were prepared for.

Colonel Blimp

The problem in May 1940 was not the resilience of the British soldier. It was the triumph of the Blimps in the interwar period. The famous cartoon character Colonel Blimp appeared regularly in London’s Evening Standard during the 1930s. The story is that cartoonist David Low was inspired to create the character after overhearing a conversation in which two military men had declared that cavalry officers should be permitted to wear spurs inside tanks. Blimp – pompous, opinionated, red-faced, resolutely opposed to change in any form – was satire, not simple invention; Low was describing a military reality.

WW2 Dunkirk British Gun Position Ruined Town May 1940
‘In battle he was tough and dogged’: so said an official German report about the British infantry they faced in May 1940. Again and again, in a collapsing strategic situation, lines were improvised and held on with grim determination. Here, British anti-tank gunners await the Panzers amid the ruins.

Briefly, in 1918, the British had had a mass national Army of citizen conscripts supplied with modern weapons and tactical doctrine. This was the Army that won the war. But the union of Army and people had been an unhappy one, and its dissolution after the war as the military shrank to a tenth or less of its former size was almost universally welcomed.

Interwar Britain was a polarised society. The economy crashed after the war amid a wave of industrial unrest. Revolution was in the air in 1919, and wage cuts later provoked the General Strike of 1926. Despite the apparent inducement of permanent mass unemployment, revulsion at the slaughter in the trenches combined with the radical mood inside the working class to discourage military enlistment.

The Army did nothing to help itself. Its deployment against striking workers at home in 1919 and 1926 and against nationalist revolt in Ireland, Egypt, and India placed it at odds with much public opinion. Renewed emphasis on drill and discipline, a redrawing of class lines between officers and men, and the rotten pay and conditions of ordinary soldiers all combined to make the Army an unattractive career choice.

The Army turned in on itself. The artillery put aside most of its heavy-calibre guns and refocused on its more mobile field equipment. The cavalry reasserted itself as a pre-eminent arm after its marginalisation on the Western Front during the war. Twenty-six battalions of tanks were reduced to four, and the discarded vehicles were left to rust in a field in Dorset.

The critics of the interwar Army were not confined to marginal mavericks. Field-Marshal Chetwode’s farewell address as Commander-in-Chief in India in 1934 included a scathing indictment of the Army he was leaving: ‘The longer I remain in the service, the more wooden and the more regulation bound do I find a British officer to be.’

The Army was, in a sense, returning to pre-war ‘normal’ – becoming again a small-wars colonial army, combining home duties with imperial policing, and having no expectation of engaging in another full-scale land war against a major modern power. In this, though, it was simply reflecting more-or-less consistent British foreign policy from 1918 to 1937.

What is the Army for?

It is misguided to pronounce from the vantage-point of hindsight that the Army should not have been run down in the way that it was during the interwar period. All societies face competing demands on resources; all decisions about how resources are allocated involve a balancing of different priorities. The victory of fascism in Germany in 1933 could not have been predicted. The relentlessness of Nazi imperialism did not become clear until the late 1930s.

Equally unfathomable was the likely shape of any future war. The RAF had become a third service in its own right in April 1918. Aerial bombing appeared to offer cut-price policing of colonial trouble-spots. The prophets of air power made chilling predictions of devastation from the air, and a British prime minister informed the House of Commons that ‘the bomber will always get through’.

Little wonder, then, that the Army became what Lord Hailsham called ‘a Cinderella of the forces’. The Royal Navy continued, of course, to play the primary role in both imperial and home-defence strategy, but the RAF now also creamed off resources, the beneficiary of a growing conviction that air power had become central to national security. To make matters worse, RAF policy was to de-prioritise tactical support of ground forces in favour of, first and foremost, building a strategic bomber force as a deterrent, and, second, with increasing urgency in the late 1930s, to create an air-defence system for the homeland.

But what was the alternative? British capitalism was in decline, its sluggish performance in the interwar period comparing badly with that of the US in the 1920s and that of Germany and Russia in the 1930s. Indeed, Britain, the original ‘workshop of the world’, was falling so far behind its competitors that it would be bankrupted by the Second World War, becoming a financial and industrial tributary of the United States by 1941. Yet the British Empire had only just reached its greatest extent: victory and Versailles had awarded it rich prizes at the expense of the defeated Central Powers. The native populations of Africa, Asia, and the Middle East, on the other hand, radicalised by the war and the wave of revolution that followed, were increasingly restless. A shrinking share of global wealth; a growing effort of imperial control: the interwar British Empire was overextended.

This is the reality behind the famous ‘Ten Year Rule’. Proclaimed in 1919, it stated: ‘It should be assumed that the British Empire will not be engaged in any great war during the next ten years, and that no expeditionary force is required for this purpose… The principal function of the military and air forces is to provide garrisons for India, Egypt, the new mandated territory, and all territories (other than self-governing) under British control, as well as the necessary support to the civil power at home…’.

Except for a growing preoccupation with air power, little changed thereafter for the best part of two decades. As late as December 1937, a meeting of the Chamberlain Cabinet listed Britain’s defence priorities as follows: first, the security of the United Kingdom, especially from air attack; second, the protection of imperial communications; third, defence of imperial possessions; and only fourth, ‘co-operation in defence of territories of any allies Britain might have in war’.

The tank problem

The effects of interwar government policy were exemplified by the tank problem. As late as 1936, the British Army was spending four times as much on horse feed as on petrol. In the May 1940 campaign, it did not have enough tanks, and those it did have were of the wrong sort and were used badly – a result of lack of spending, lack of experience, and lack of doctrine in relation to armoured forces over the preceding two decades.

Ironically, of course, the British had pioneered the development of the tank, and, unsurprisingly therefore, had produced two leading advocates of armoured warfare in Colonel (later Major-General) John ‘Boney’ Fuller (1878-1966), who had served as chief staff officer in the Tanks Corps during the First World War, and Captain Basil Liddell Hart (1895-1970), who fought as an infantry officer in the trenches.

By the early 1930s, Fuller was arguing that the relatively immobile linear battlefield of the First World War, in which mass conscript armies confronted one another across clearly defined ‘no-man’s-land’, was a thing of the past. Henceforward, the typical battlefield would comprise an entire region in which small, mechanised, highly trained armies would manoeuvre in depth, supported by aircraft, and pivoting on dispersed strong-points, anti-tank bastions, and defended supply-bases.

Liddell Hart’s emphasis was different, but the main thrust of his argument pointed in the same direction. Reflecting on the ‘infiltration’ tactics employed on the Western Front in 1918, he extrapolated that these would become decisive with the further development of armour, air power, and lorry-borne infantry; the ease and speed of mechanised breakthroughs would produce ‘expanding torrents’ of men and firepower spreading out across the enemy rear, destroying the battlefield’s traditional linear configuration.

The German Blitzkrieg of May 1940. While Leeb’s Army Group C fixed the French garrison of the Maginot Line on the Franco-German frontier, and Bock’s Army Group B advanced into Belgium and fixed the main Allied masse de manoeuvre coming to meet them, the decisive breakthrough was made by nine armoured divisions lunging through the Ardennes towards the Meuse crossings near Sedan. Ten days after the start of the offensive, seven days after their first elements crossed the Meuse, the Panzers reached the sea, cutting the Allied armies in half. A triumph of organisation and doctrine, it was one of the greatest victories in military history.

The problem was that you could not guard the sea-lanes with a tank, nor deter an enemy bomber. Equally, the heavier armoured vehicles were far from ideal if the priority was policing a nationalist demonstration or suppressing a tribal rebellion on a remote frontier. In consequence, the resources were not made available to develop an armoured warfare capacity in the interwar years.

Lack of experience led to muddle over design, organisation, and doctrine. Armoured vehicles could be used in various ways – for colonial policing, for reconnaissance and screening, in close infantry support, and as armoured spearheads if massed in independent mechanised formations. So what sort of tank is ideal?

The British entered the Second World War with two main types: heavily armoured ‘I’ tanks that moved at walking pace, had light armament, and were designed for close co-operation with attacking infantry; and lightly armoured ‘cruiser’ tanks that were fast but still lacked heavy armament, as they were intended mainly for reconnaissance, screening, and other light duties. Neither fitted the demands of May 1940.

The Germans, by contrast, had already developed the concept of a main battle tank – an ideal design that attempted to combine speed, robustness, protection, gun-power, and ease and cheapness of manufacture. Achievement may still have fallen well short of aspiration, but the thinking was sound, as was the grouping of tanks in independent Panzer divisions, and the concentration of these armoured divisions at the point d’appui (the ‘fulcrum’ of the battlefield).

General Gort’s army

The British Expeditionary Force that fought the Dunkirk campaign bore all the hallmarks of interwar policy. The military establishment had plunged from 3.5 million in 1918 to 370,000 by the end of 1920. Further drastic reductions followed in 1922, and thereafter the Army budget fell steadily every year from £43.5 million in 1923 to just under £36 million in 1932.

These reductions reflected the Ten Year Rule, the assumption that Britain would not be obliged to form an ‘expeditionary force’ to wage war on the Continent in the foreseeable future. The policy did not change even with the growing threat to British interests during the 1930s from Imperial Japan in the Far East, Fascist Italy in the Middle East, and Nazi Germany in Central Europe. Appeasement dominated policy until virtually the end of the decade, mainly because most of Britain’s rulers continued to regard revolution and Stalin’s Russia as greater dangers than fascism and German imperialism.

By 1937, however, the policy was beginning to change. Leslie Hore-Belisha was appointed Secretary of State for War when Chamberlain became Prime Minister in May 1937, and he set about modernising Britain’s armed forces. Pay and conditions were improved, conservative generals were sidelined, and Liddell Hart was brought in as an unofficial government advisor.

The wind of change strengthened during 1938 and the first half of 1939, as it became clearer that appeasement was failing in the face of Nazi rearmament and aggression. The military budget shot up, a limited form of conscription was introduced, and spending on new equipment meant that when war broke out the British Expeditionary Force – initially 160,000 men and 23,000 vehicles – was the only fully motorised army on the Continent.

The ‘Phoney War’ between September 1939 and May 1940 allowed the belated military build-up to continue, such that the BEF had swelled to around 400,000 by the time the serious fighting began.

It was commanded by General Viscount John Vereker Gort VC, a living symbol of the Old Guard’s return to power. General Alan Brooke described him as ‘the best platoon commander in France’. A guardsman and very much a regimental soldier, he had, in British Army historian Allan Mallinson’s opinion, ‘risen by that private Household elevator which had once been a feature of the Army’. Consequently, in May 1940, as a whirlwind armoured Blitzkrieg engulfed his army, he was soon ‘out of his depth’.

WW2 Dunkirk Allied Troops Wading To Clyde River Steamer May-June 1940
Allied troops wading out to a waiting Clyde river steamer.

Blitzkrieg On 13 May 1940, General Heinz Guderian’s XIX Panzerkorps crossed the River Meuse at Sedan and entered French territory. Supported by pioneer assault units and screaming dive-bomber attacks, his three Panzer divisions (1st, 2nd, and 10th) smashed through weak French defences in a sector where no attack had been expected. Somewhat earlier on the same day, a short distance further north, General Erwin Rommel’s 7th Panzer Division had also crossed the Meuse at Dinant.

It was just three days since the start of the German attack in the West. The Panzers had passed through the Ardennes Forest, widely assumed to be impenetrable to armoured columns, in order the strike the weakest point in the French line – the hinge between the main mass of the Allied armies advancing into Belgium to the north and the formidable Maginot Line defences along the Franco-German border to the south.

The German plan had been conceived by General Erich von Manstein. It had faced determined opposition from more conservative generals. Their preferred plan was the one that had failed in 1914: a massive turning movement through Belgium and north-eastern France directed at Paris. The Allied plan was a mirror-image of this: to hold the Maginot Line in moderate force and to direct a vast mobile army into Belgium to confront the German attack head-on. The widely expected outcome was stalemate and attrition in the traditional cockpit of European conflict.

Few German officers could see the potential of mobile armoured warfare. Blitzkrieg – ‘lightning war’ – was a combination of advanced industrial technology and radical military thinking. Both were necessary. In spring 1940, the French had more tanks and fighter-aircraft than the Germans. But they did not deploy them according to a new conception of war. Nor, until the last minute, did the Germans. Then, Hitler’s personal intervention, driven primarily by his deep-rooted fear of a war of attrition, led to the adoption of the Manstein plan. Instead of being concentrated in the north for the invasion of Belgium, the German armour was massed at the far edge of the Ardennes.


During 14 May, the Panzer generals expanded and strengthened their bridgeheads over the Meuse, beat off poorly managed French counter-attacks, and then pushed their armoured spearheads westwards. Henceforward, they kept moving, ignoring the evolving threat to their f lanks and line of communication as they drove deeper into northern France. The theory was that the speed of the advance and the disruption to the enemy’s command and communication systems would prevent the concentration and co-ordination necessary for a successful counterattack.

So it proved. Keeping the River Somme on their left as a defensive barrier, the Panzers drove for the Channel ports. On 20 May they reached the sea near Abbeville. On 25 May they captured Boulogne. On the 26th, Calais.

As early as the morning of 15 May, the French Prime Minister, Paul Reynaud, had woken Churchill with a phone call to announce, ‘We are beaten. We have lost the battle.’ He was correct. With a wide gap torn in the French line and the German armour racing towards the Channel, it was only a matter of days before the supply-line of the Allied army advancing into Belgium would be severed. As soon as that happened, it would begin to disintegrate, like a vast complex machine whose power is suddenly switched off.

Dunkirk Pocket map
The Dunkirk pocket. The defence of the shrinking perimeter and the management of the retreat to the sea and the maritime evacuation were masterly, especially given the surrender of the Belgian Army and the moral collapse of much of the French Army in the closing stages of the campaign.

The speed and completeness of the German victory had thrown everyone – the Germans included – off balance. The military situation had been transformed beyond any expectations. No-one had planned for this. Improvisation was now the order of the day. Contingency – the mix of accident and on-the-spot decision that often decides history’s direction – now determined, however, that the British Army would not be destroyed.

Five factors were decisive: the anxiety and vacillation of German high command; the intelligence and energy of some senior British officers in managing the defence of the shrinking perimeter around the trapped BEF; the gritty resilience of British soldiery when operating defensively with their backs to the wall; Gort’s decision to disobey orders from London and organise an immediate fighting retreat to Dunkirk; and the dynamic brilliance of Admiral Ramsay’s improvised armada of rescue vessels.

Calais had fallen on 26 May, and the assumption was that the Panzers would now race eastwards to take the two remaining Channel ports of Dunkirk and Ostend, sealing the head of a bag of territory containing around half a million French, British, and Belgian soldiers.

But they did not. Hitler ordered the Panzers to halt. Debate about his reasons continues. So, too, does debate about the significance of this decision. Some consider it the turning-point in the Second World War. What is certainly true is that it gave to the British that crucial window of time that enabled them to save their army and continue the war.

Most immediately, the German halt order enabled Gort to shift two divisions onto his left f lank to plug the gap created when the Belgians surrendered. But this also meant abandoning any further possibility of mounting an effective counterattack with the French against the Panzer corridor. The BEF was now fighting a wholly defensive battle along the perimeter of a pocket of land around the port of Dunkirk.


Already, as early as 19 May, the British and French navies had been instructed to prepare sea transport for the besieged armies. At Dover, Vice-Admiral Bertram Ramsay set up Operation Dynamo. No sooner had he done so than his options began shutting down, with the loss of first Boulogne, then Calais. The evening Calais fell, the Admiralty signalled Ramsay that Operation Dynamo should commence immediately. Perhaps, with sufficient vigour, as many as 45,000 of Gort’s trapped men might be brought home.

Allied troops queuing on the Dunkirk beaches for their turn to be ferried to a transport. Despite repeated air-attacks and the knowledge that the perimeter around the beachhead was under siege, discipline and solidarity remained unbroken to the very end.

In fact, Ramsay was ahead of his superiors: he had already started evacuating non-essential personnel. In another respect, too, he now took matters into his own hands. Dunkirk’s port facilities were soon out of commission, and the Admiral realised that he would have to take men straight off the beaches. On his own authority, therefore, he began requisitioning small boats, and searching out men who could sail them.

At Dunkirk itself, the Senior Naval Officer Ashore was also improvising. With the lack of port facilities and the disruption from German air attack, he had decided to speed up evacuation by utilising a flimsy wooden pier, the East Mole, 5-feet wide, stretching about 1,400 yards into the sea.

Henceforward, Royal Navy destroyers went one after the other to the East Mole to load up with men, while the small boats ran in and out from the beaches, passing between the lines of soldiers waiting waist-deep for their turn to be taken to the bigger ships anchored out to sea that would carry the Tommies home.

The Luftwaffe attacks were relentless, strafing and bombing the ships, the beaches, the Mole, and the throngs of men backed up around the port. The worst of it was when they hit a ship laden with men packed tight together on the decks. The surf, smeared oily black and blood-red, bobbed with bodies and bits of ship. The small boats weaved their way through corpses and wrecks to make a passage for the living.

It went on for days. Observers noted the patience of the soldiers, the professionalism of the Royal Navy crews, and the courage of the civilians crewing the small boats. There was criticism of the Royal Air Force for its poor showing against the Luftwaffe, but it was not entirely fair – 177 British aircraft were lost in the struggle to protect the beaches.

WW2 Dunkirk Small Boats May-June1940
Hundreds of small civilian vessels ferried Allied soldiers from the beaches to the larger ships waiting off shore – and sometimes all the way home across the Channel.

Retreat to victory

In the end, 230,000 men were taken off the East Mole, and another 100,000 off the beaches. On the final day, 3 June, the plan was to rescue the 30,000 French soldiers of the rearguard, who had kept the Germans at bay, holding the shrinking rim of the Dunkirk perimeter long enough to complete the evacuation. But when the time came, an estimated 40,000 soldiers emerged from the basements and ruins of Dunkirk, and very few of the valiant rearguard were among the last 26,000 evacuees.

Six destroyers, eight personnel ships, and over 200 small craft were lost during the evacuation. Left behind was virtually all of the BEF’s heavy equipment – some 600 tanks, more than 1,000 field or heavy guns, 500 anti-aircraft guns, 850 anti-tank guns, many thousands of anti-tank rif les, large numbers of lorries, cars, and motorbikes, and huge quantities of ammunition and supplies.

But a third of a million men had been rescued. Two-thirds of them were British, and these 224,000 trained soldiers gave Britain its fighting chance. Without them, there would have been no army to prevent an invasion. Without them, there were would have been no military nucleus around which to build the mass citizen armies to come.

The campaign of May-June 1940 produced two of the most astonishing events in military history. One was the German armoured breakthrough between 13 and 20 May that trapped the main Allied army in Belgium and ensured the Nazi conquest of France. The second was the seaborne evacuation, against all the odds, of a third of a million soldiers – the men who, together with those of the Royal Navy and the RAF, would now prevent a Nazi conquest of Britain.

This article appeared in issue 31 of Military History Monthly. To subscribe to the magazine, click here.

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