Operation Unthinkable – Churchill’s plan that would have started World War 3

According to Field Marshal Montgomery, rule number one on the first page of the book of war is ‘do not march on Moscow’.

In April 1945, Winston Churchill ordered the British Chiefs of Staff to rip up the rule book and plan for an attack on their wartime ally, Russia.

It was audacious, inconceivable and incredibly risky.

So, fittingly, it was codenamed Operation Unthinkable.

Just how close did we come to launching the Third World War in 1945?

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A naughty document

In October 1944, Winston Churchill and Josef Stalin met for the Fourth Moscow Conference. During a long evening of vodka-fuelled negotiations, the two leaders agreed to divide various European countries into spheres of influence.

Churchill wrote out a list of countries and percentages to represent the interests of the USSR and the UK. Stalin indicated his approval of the plan by marking a large blue tick in the top corner.

This possibly represented the high point in Churchill’s faith in his Russian wartime ally.

Just five months later, serious doubts had surfaced in Churchill’s mind over whether the Soviet Union could be trusted. At stake was the future of Poland, the post-war division of Europe and even the survival of western democracy.

In 1939, Britain had gone to war with Nazi Germany in fulfilment of the terms of the Anglo-Polish Agreement of Mutual Assistance. Now, with the end of the war in sight, Churchill had a keen interest in the fate of her pre-war ally.

Josef Stalin also had a keen interest in the fate of Poland.

And Stalin exerted far more control over what that its future would be.

By the time the Allied leaders met at Yalta in February 1945, the Red Army was in control of most of Poland. It had occupied Warsaw, Lodz and Krakow, or, at least, what remained of these cities. It was also posed to take Berlin, Vienna and Prague, tightening the Soviet grip on central Europe.

Stalin had also installed the Polish Committee of National Liberation in power in Warsaw. The Committee, also known as the Lublin Government, was dressed in the costume of national independence, but was fully controlled from Moscow.

Any doubt about Stalin’s intentions was relieved when 16 Polish representatives of the London-based government-in-exile were arrested despite having been issued safe-conduct passes.

Churchill’s doubts solidified as Soviet intransigence increased. He expressed his fears to Roosevelt that: ‘at present all entry into Poland is barred to our representatives. An impenetrable veil has been drawn across the scene’.

So had Britain gone to war with one totalitarian state only to see another take control of Poland?

A tide of Russian domination is sweeping forward

On 4 May 1945, Churchill wrote to the Foreign Secretary, Antony Eden:

‘Terrible things have happened. A tide of Russian domination is sweeping forward … After it is over, the territories under Russian control will include the Baltic provinces, all of eastern Germany, all Czechoslovakia, a large part of Austria, the whole of Yugoslavia, Hungary, Romania and Bulgaria.

‘This constitutes one of the most melancholy events in the history of Europe and one to which there has been no parallel. It is to an early and speedy showdown and settlement with Russia that we must now turn our hopes.’

What kind of ‘early and speedy showdown’ could Britain hope for in 1945?

In 1941, Churchill had assumed that victory would bring with it the triumph of the Anglo-Saxon world, with the USA and the British Empire to be the driving engines of a new world order. Churchill predicted that the Soviet Union would: ‘need our aid for reconstruction far more than we shall need theirs’.

It didn’t work out like that. By the end of the war, Britain was broken in victory. The Red Army controlled eastern Europe and had over seven million men under arms. And it was only going to get worse. Churchill pondered the future:

‘What will be the position in a year or two, when the British and American Armies have melted and the French has not yet been formed on any major scale, when we may have a handful of divisions, mostly French, and when Russia may choose to keep two or three hundred on active service?’

And then what?

Could Britain once again face an enemy just across the narrow divide? Churchill went on to muse that:

‘it would be open to the Russians in a very short space of time to advance, if they chose, to the waters of the North Sea and the Atlantic’.

On VE-Day, the Prime Minister broadcast to the British people to tell them that the war in Europe was over. Crowds filled the streets and squares of a jubilant London. Max Hastings recounts Churchill’s mood amidst this celebration:

‘From a balcony in Whitehall that evening, he addressed a vast, cheering crowd, who sang Land Of Hope And Glory and For He’s A Jolly Good Fellow. But back in his rooms, all he could talk about was his dismay at Soviet barbarism in the east’.

To impose upon Russia the will of the United States and the British Empire

Diplomacy had failed. Communist regimes were tightening their grip on power throughout central and eastern Europe. Agreements on British and American access to Prague, Vienna and Berlin were ignored.

Just under a month before Germany’s final surrender, Winston Churchill ordered the British Armed Forces’ Joint Planning Staff to think the unthinkable and plan for an attack on Russia.

Lt Gen Sir Hastings Ismay submitted his final report to Churchill on 22 May 1945. In it, the primary goal of Operation Unthinkable was stated as being:

‘to impose upon Russia the will of the United States and the British Empire. Even though ‘the will’ of these two countries may be defined as no more than a square deal for Poland, that does not necessarily limit the military commitment.

There was even a target date for the offensive. British and American tanks would roll eastwards once again on 1 July 1945.

The plan was based on some key assumptions.

The attack would enjoy the full backing of the public in the UK and USA and continued high morale amongst British and American troops.

The western allies would full assistance from Polish troops and recourse to German manpower and the remnants of German industrial capacity and they could rely on logistic support from other western countries.

Finally, the planner assumed that, on being attacked, Russia would ally herself with Japan;

One of the more incendiary aspects of the plan was that the western allies were to be joined by up to 100,000 rearmed German soldiers. The planners were told to: ‘count on the use of German manpower and what remains of German industrial capacity’.

The plan called for a swift punch through Poland by 47 British and American divisions. The Royal Air Force would strike from bases in Denmark and Northern Germany and the Royal Navy would move along the Baltic coast.

What would have happened next?

The Paris Peace Talks

What if … Churchill had convinced his generals and the Americans that they needed to attack the Soviet Union in July 1945? This section imagines a possible outcome for this future that never was.

Stalin strode across the square. He was aware of the entourage hustling behind him, but he didn’t look back. He had arrived in Paris after a three-day train journey crawling through the blasted, ruined towns and cities of Europe and he was keen to stretch his legs.

He had observed the destruction with grim satisfaction. First the Germans and then the Imperialists had tried to grind Russia into dust. But it was not mighty Russia that had been ground down. Instead, the Red Army had continued its westward march until it reached the Atlantic. Not even Tsar Alexander had reached the Atlantic.

Stalin hadn’t been caught out by Churchill’s perfidy and Truman’s treachery. He had known all along that after Germany had been defeated, America and England would turn on Russia.

They had expected the Soviet Union to bleed to death. Nazi Germany and Communist Russia were supposed to have exhausted each other. But it wasn’t Russia who had emerged battered and broken. Britain didn’t have the resources for another fight and America didn’t have the stomach.

Stalin had been determined not to be caught out again. He still had nightmares about the dark days in June 1941 when Hitler had unleashed his armies against him. That would never happen again.

He had given Merkulov all of the resources that the People’s Commissariat for State Security needed to infiltrate the Imperialists. His spymaster ensured that they had people in Downing Street, at the White House and, perhaps most importantly, at Los Alamos.

This time, Stalin had known the day of the planned attack and his forces were ready. Marshal Zhukov had regrouped his forces around Berlin and Brandenburg. The Red Army had hastily dug itself-in and built defences. Tanks and aircraft were moved north and west. They were ready.

He had been lost in thought, but no one around him dared to interrupt his silence. Eventually, Stalin was roused by the clipped sounds of a parade drill. He looked up and around. He was here to inspect preparations for the peace talks.

His advisors had suggested holding the talks at Versailles. Stalin rejected that – he’d hated Potsdam and wasn’t going to repeat the experience of being holed up in an aristocrats’ playground.

No, the talks would be in Paris. And he knew exactly the right location. The Communards had established a headquarters at the Hôtel de Ville. That would send the right signal to the Capitalists. He had decided that Kaganovich and Zhdanov were the most capable Orgburo members available and had charged them with organising the spectacle.

The square was already surrounded by a phalanx of oversized flagpoles, each bearing a huge red flag. The town hall had been dressed with red banners and illuminated portraits of Marx, Lenin and Stalin. As soon as the square was lined with Red Army soldiers, the effect would be overpowering.

He was now really enjoying himself. He would make little Clement Attlee and President Rayburn walk the entire length of the square towards the meeting, long enough to impress upon them the new reality of power in Europe.

Churchill had been turfed out of office as soon as it became clear that his gamble had gone wrong. The British Army had made a few small gains in north Germany, but were soon pushed back. Whole companies of British and American troops had mutinied. They might not have been so keen to give up if they knew the welcome that Mother Russia was preparing for them back in Siberia.

Within days, the retreat had become a rout and the Imperialists were rapidly chased out of Germany. In the end, the remnants of their armies almost retraced their steps, falling back to the same Normandy beaches they had triumphantly landed upon just over a year ago.

Those precious little ships had, once more, ferried back the broken divisions of soldiers. But this time, the weather had not been kind and thousands had drowned in storms that ravaged the Channel.

All that was left was for Stalin to decide how much of Europe he would absorb directly into the Soviet Union. The rest would be given reliably Communist governments. He would then decide how to dismember the British Empire – he was particularly keen to see a Russian naval base in Newfoundland.

He walked into the town hall and was met with a decidedly sweaty looking Beria. He looked terrified and all the colour had drained from his face. Normally, He fixed his poisonous dwarf with a stare. Beria had a habit of not speaking unless you beat the truth out of him.


Beria shifted and looked at the ground. Stalin grabbed his shoulders and forced him to meet his gaze.

“There has been news …


“from Moscow. And Leningrad …”

“Spit it out, Beria, the Devil got you?”

“They’ve dropped it. They’ve dropped the bomb.”

Committed to a protracted war against heavy odds

The military’s response to Churchill’s call to think the unthinkable was unambiguous and unpromising.

They informed the Prime Minister that an attack on Russia at this stage ran a strong risk of failing.

This was putting it mildly.

At the time, the USSR had a two to one superiority in armour and four to one in infantry across Europe and the Middle East.

The result of such failure would be the occupation of the entire European continent by the Soviet Union and the possible loss of British independence. Many hundreds of thousands if not millions of further lives would be lost.

A plan was submitted to the Prime Minister on 8 June 1945, in which the Chiefs of Staff wrote: ‘once hostilities began, it would be beyond our power to win a quick but limited success and we should be committed to a protracted war against heavy odds’.

Victory would be impossible without: ‘a large proportion of the vast resources of the United States’. The remote odds would:

‘become fanciful if the Americans grew weary and indifferent and began to be drawn away by the magnet of the Pacific war’.

Field Marshal Brooke was less diplomatic, writing that: ‘the idea is, of course, fantastic and the chances of success quite impossible. There is no doubt that from now onwards Russia is all powerful in Europe.’

The Cabinet Office planners also pointed to the failure of Nazi Germany’s invasion of the Soviet Union to highlight the futility of such a military engagement.

Unsurprisingly, the report suggested that the Soviet Union was likely to respond aggressively to such an attack. Whilst the allies concentrated on Poland, the Red Army could overrun Norway, Turkey, Greece and potentially take the oil fields of Persia and Iraq.

War weariness will be the predominant feature

Even if Churchill had got the top brass on board, how could they possibly convince soldiers and civilians to make further sacrifices?

Fighting in the west had been destructive enough, but it was nothing compared to the blood that had already soaked eastern Europe and the western Soviet Union. If anyone knew that, it was the Germans. The report suggests that:

‘war weariness will be the predominant feature of the German civil population’.

The planners feared outright mutinies in the British army if they were told to prepare for war with their erstwhile allies.

General Hastings Ismay thought it impossible even to contemplate asking them. Could Britain and America forget:

‘all that they had said about their determination to destroy Nazism, taken the Germans into their fold, and proceeded, with their help, to crush their recent allies? One is forced to the conclusion that such a reversal of policy … was absolutely impossible for the leaders of democratic countries even to contemplate.’

Ismay went on to write:

‘For over three years, public opinion in America and Britain had been led to believe that Russia was a brave and faithful ally who had done the lion’s share of the fighting, and endured untold suffering. If their governments had now proclaimed that the Russians were untrustworthy and unprincipled tyrants, whose ambitions must be held in check, the effect on national unity in both countries would have been catastrophic’.

Was Churchill’s bellicosity, in part, fuelled by his knowledge of the successful progress of the Manhattan Project? His state of mind may have been revealed at July’s Potsdam conference, Churchill told the Chief of the Army, Sir Alan Brooke:

‘if they insist on doing this or that, well we can just blot out Moscow, then Stalingrad, then Kiev and so on’.

In the end, the preparations came to nothing, and were, if anything counterproductive, serving only to fuel increasing suspicion between the wartime allies. The discussions were conducted with the greatest levels of secrecy. But this didn’t prevent Stalin soon finding out about them. Soviet agents and communist sympathisers had penetrated all levels of the Whitehall bureaucracy.

Moscow was told of the planning and was also informed that Field Marshal Montgomery had been ordered to gather up German arms in case they were needed to re-arm Wehrmacht troops.

The plan’s obvious flaws and difficulties did not end discussions. As tensions began to increase between the west and the Soviet bloc, British and American military planners began to consider how they would defend Western Europe and the British Isles from any Russian attack.

Churchill responded to ask his military planners to:

‘Pray have a study made of how then we could defend our island, assuming France and the Low Countries were powerless to resist the Russian advance to the sea’.

The details of the planning were stored away at the Public Records Office in a file headed ‘Russia: Threat to Western Civilisation’.

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