With the defeat of Nazi Germany more or less certain in February 1945, British Prime Minister Winston Churchill praised his Russian counterpart Joseph Stalin as a ‘friend whom we can trust’.
He was speaking at the Yalta Conference, where the two men were joined by US president Franklin Roosevelt to discuss the post-war reorganisation of Europe after the Soviet Union’s central role in overcoming Adolf Hitler.
But when Soviet troops captured Berlin in May 1945 and Stalin showed no willingness to relinquish his control of Central and Eastern European countries, Churchill ordered the creation of a plan that would plunge the world into another devastating conflict.
The astonishing blueprint – officially named Operation Unthinkable – outlined how British and American forces would embark on a ground, air and naval offensive against their ally the Soviet Union.
The War Cabinet files outlining the plan – and the recorded horror of military chiefs which ultimately killed it off – were declassified in 1998 and now sit in the National Archives.
The blueprint acknowledged the horrendous odds – the Soviets had 170 military divisions, compared to Britain the US’s combined 47.
To redress the balance, the plan’s architect – Brigadier Geoffrey Thompson – even proposed rearming troops from the Wehrmacht and murderous Nazi SS, who had been in charge of the death camp network which carried out the Holocaust.
Operation Unthinkable is outlined in historian Giles Milton’s new book Checkmate in Berlin, which is being published on Thursday by John Murray Press.
With the defeat of Nazi Germany more or less certain in February 1945, British Prime Minister Winston Churchill praised his Russian counterpart Joseph Stalin as a ‘friend whom we can trust’. He was speaking at the Yalta Conference, where the two men were joined by US president Franklin Roosevelt to discuss the post-war reorganisation of Europe after the Soviet Union’s central role in overcoming Adolf Hitler
![But when Soviet troops captured Berlin in May 1945 and Stalin showed no willingness to relinquish his control of Central and Eastern European countries, Churchill ordered the creation of a plan that would plunge the world into another devastating conflict](https://i.dailymail.co.uk/1s/2021/05/25/15/43415419-9616487-image-a-60_1621952224047.jpg)
But when Soviet troops captured Berlin in May 1945 and Stalin showed no willingness to relinquish his control of Central and Eastern European countries, Churchill ordered the creation of a plan that would plunge the world into another devastating conflict
Churchill ordered his joint planning staff to draw up the blueprint at the beginning of May in 1945, shortly after Hitler had committed suicide and the Red Army had captured Berlin.
The papers in the National Archives reveal how the aim of the plot was to impose on Russia the ‘will of the United States and British Empire.’
Milton writes of the ‘remarkable’ level of detail in the plan. It included tables, charts and maps, along with tables listing the strength of both the Soviet and Allied forces.
From July 1,1945, Allied forces would launch a surprise attack on Stalin’s forces, pushing the Red Army back to the Oder and Neisse rivers, 55 miles east of Berlin.
By this point, Soviet troops were occupying Berlin and had control of Eastern Europe, including Poland.
The Western assault, which would be the largest tank offensive in history with 8,000 armoured vehicles used, would end with a huge showdown in the countryside in Soviet-occupied Pila, in what is now north-west Poland.
Despite the significant difference in the number of Allied divisions when compared to their potential adversaries, Thompson outlined how naval superiority would be used to good effect – with a seizure early on of the Baltic port of Stettin.
Thompson hoped that stopping Western exports to Russia would cripple its military. Milton explains that the Soviet Union was dependent on America for explosives, as well as rubber, aluminium, copper and 50 per cent of its aviation fuel.
![From July 1,1945, Allied forces would launch a surprise attack on Stalin's forces, pushing the Red Army back to the Oder and Neisse rivers, 55 miles east of Berlin. By this point, Soviet troops were occupying Berlin and had control of Eastern Europe, including Poland](https://i.dailymail.co.uk/1s/2021/05/25/15/43418907-9616487-image-a-71_1621952474336.jpg)
From July 1,1945, Allied forces would launch a surprise attack on Stalin’s forces, pushing the Red Army back to the Oder and Neisse rivers, 55 miles east of Berlin. By this point, Soviet troops were occupying Berlin and had control of Eastern Europe, including Poland
![](https://i.dailymail.co.uk/1s/2021/05/25/15/43422345-9616487-image-a-63_1621952248408.jpg)
![](https://i.dailymail.co.uk/1s/2021/05/25/15/43422341-9616487-image-a-64_1621952288081.jpg)
![The astonishing blueprint – officially named Operation Unthinkable – outlined how British and American forces embark on a ground, air and naval offensive against their erstwhile ally the Soviet Union](https://i.dailymail.co.uk/1s/2021/05/25/15/43422339-9616487-image-a-66_1621952296282.jpg)
The astonishing blueprint – officially named Operation Unthinkable – outlined how British and American forces embark on a ground, air and naval offensive against their erstwhile ally the Soviet Union
However, he warned that the Russian Army’s ‘capable’ high command had a ‘disregard for losses’ when trying to obtain a ‘set objective’.
He warned Churchill that, if they were to proceed, they would be ‘staking everything’ on one epic battle where the odds would be ‘very heavy’.
It was for this reason that he proposed re-arming the Wehrmacht and the SS. Doing so would add another ten divisions, all of which would be made up of men hardened by six years of war.
Despite level of detail in the plan – and the time and effort which went into devising it – Churchill’s military chiefs were horrified by it.
Field Marshal Sir Alan Brooke said Allied troops would end up ‘committed to a protracted war against heavy odds’.
General Hastings Ismay was disgusted by the idea of using Hitler’s defeated troops. He said it would be ‘absolutely impossible for the leaders of democratic countries even to contemplate.’
He said the Russians had done the ‘lion’s share of the fighting and endured untold suffering’.
![The plan acknowledged the horrendous odds – the Soviets had 170 military divisions, compared to Britain the US's combined 47. Pictured: Red Army soldiers on the attack against German forces during the Battle of Kursk in July 1943](https://i.dailymail.co.uk/1s/2021/05/25/15/43414181-9616487-image-a-75_1621952630884.jpg)
The plan acknowledged the horrendous odds – the Soviets had 170 military divisions, compared to Britain the US’s combined 47. Pictured: Red Army soldiers on the attack against German forces during the Battle of Kursk in July 1943
![Churchill told his Foreign Secretary Anthony Eden that if Stalin's territorial desires were not dealt a definitive blow 'before the US armies withdraw from Europe and the Western world folds up its war machines, there is very little prospect of preventing a Third World War.' Pictured: Churchill pulls out a new cigar as Stalin smiles behind him at the Yalta conference](https://i.dailymail.co.uk/1s/2021/05/25/15/43414179-9616487-image-a-72_1621952498175.jpg)
Churchill told his Foreign Secretary Anthony Eden that if Stalin’s territorial desires were not dealt a definitive blow ‘before the US armies withdraw from Europe and the Western world folds up its war machines, there is very little prospect of preventing a Third World War.’ Pictured: Churchill pulls out a new cigar as Stalin smiles behind him at the Yalta conference
![The plan's architect - Brigadier Geoffrey Thompson - even proposed rearming troops from the Wehrmacht and murderous Nazi SS, who had been in charge of the death camp network which carried out the Holocaust. Pictured: German commanders, including General Alfred Jodl seated with his back to the camera, sign surrender documents in Reims, France, ending the war in Europe](https://i.dailymail.co.uk/1s/2021/05/25/15/43424021-9616487-image-a-83_1621953891600.jpg)
The plan’s architect – Brigadier Geoffrey Thompson – even proposed rearming troops from the Wehrmacht and murderous Nazi SS, who had been in charge of the death camp network which carried out the Holocaust. Pictured: German commanders, including General Alfred Jodl seated with his back to the camera, sign surrender documents in Reims, France, ending the war in Europe
To attack them so soon after the end of the horrendous conflict would be ‘catastrophic’ for morale.
More than 27million Russians – both civilians and combatants – had died during the conflict, far more than Britain’s casualty figure of around 450,000 and the US’s 407,000.
![Checkmate in Berlin, by Giles Milton, is published on May 27](https://i.dailymail.co.uk/1s/2021/05/25/15/43422835-9616487-image-a-90_1621954560498.jpg)
Checkmate in Berlin, by Giles Milton, is published on May 27
Most historians agree that it was Russia’s resistance to Nazi Germany’s attempted invasion – leading Hitler to fight a war on two fronts – which sealed the country’s defeat.
Field Marshal Brooke added that the chance of success of Operation Unthinkable was ‘quite impossible’.
On June 8, Churchill’s chiefs of staff officially rejected the plan.
However, the PM – who was to be turfed out of office a little over a month later in the 1945 General Election – was not happy with the death of the plan.
Milton outlines how Churchill told his Foreign Secretary Anthony Eden that if Stalin’s territorial desires were not dealt a definitive blow ‘before the US armies withdraw from Europe and the Western world folds up its war machines, there is very little prospect of preventing a Third World War.’
Churchill also warned his military chiefs that the Red Army would soon become impossible to beat.
He said: ‘At any time that it took their fancy, they could march across the rest of Europe and drive us back into our island.’
The Operation Unthinkable file claims that the plan had the ‘full support of public opinion in the British Empire and the United States’ – a nod to general concern about the growing power of the Soviet Union.
Brigadier Thompson warned that the conflict might develop in a way which allowed Soviet troops to withdraw into Russia without suffering ‘decisive defeat’.
![General Hastings Ismay said it would be 'absolutely impossible for the leaders of democratic countries even to contemplate' attacking the Soviet Union. He said the Russians had done the 'lion's share of the fighting and endured untold suffering'](https://i.dailymail.co.uk/1s/2021/05/25/15/43415425-9616487-General_Hastings_Ismay_said_it_would_be_absolutely_impossible_fo-m-78_1621953531292.jpg)
General Hastings Ismay said it would be ‘absolutely impossible for the leaders of democratic countries even to contemplate’ attacking the Soviet Union. He said the Russians had done the ‘lion’s share of the fighting and endured untold suffering’
![After Operation Unthinkable was rejected, Churchill warned that the Red Army would soon become impossible to beat. Pictured: Churchill meets with Stalin in 1943](https://i.dailymail.co.uk/1s/2021/05/25/15/43415453-9616487-image-a-80_1621953542029.jpg)
After Operation Unthinkable was rejected, Churchill warned that the Red Army would soon become impossible to beat. Pictured: Churchill meets with Stalin in 1943
![Field Marshal Brooke (pictured above) added that the chance of success of Operation Unthinkable was 'quite impossible'](https://i.dailymail.co.uk/1s/2021/05/25/15/43419069-9616487-image-m-87_1621954129686.jpg)
Field Marshal Brooke (pictured above) added that the chance of success of Operation Unthinkable was ‘quite impossible’
If this were to happen, he added that there was ‘virtually no limit to the distance to which it would be necessary for the Allies to penetrate into Russia in order to render further resistance impossible’.
Laying out the bleak outlook further, he said that even if it were to go according to plan’, ‘the military power of Russia will not be broken and it will be open to her to recommence the conflict at any time she sees fit’.
As for the US, President Harry Truman – who came to office after the death of Roosevelt in April 1945 – made it clear in a military cable that there was no possibility that Americans would lead an effort to drive Russian troops from Poland by force.