Why were the Germans and Russians so fixated on an unlikely "separate peace" in 1945?

One has to keep in mind that the alliance between the UK, the US, and the USSR was always a very uneasy one. Two forms of government diametrically opposed to each other, forced together by circumstance. They shared nothing in common, other than a desire to defeat Germany.

The basic premise that the US and UK might make a separate peace with Germany was predicated on that uneasy alliance, and divergent forms of government. The very concept of communism, before it became apparent that the communist governments had their own form of corruption, was anathema to the capitalist western nations.

This never became reality, with nuclear weapons forestalling actual combat between the Soviets and the western nations through the concept of MAD: mutually assured destruction.

So, to return to the original question - why were Germans and Russians fixated on a separate peace? Because, due to the divided interests of the Soviets and the UK/US, it was a possibility, one that might have worked to the advantage of the Germans.

I mean, apart from the fact the British and Americans met, planned, collaborated, shared intelligence etc separately from the Russians, which, yes, was a problem for the Soviet Union

Stalin in his letter to Roosevelt on 7th April 1945 cited yet another reason to doubt the loyalty of USA:

It is hard to agree that the absence of German resistance on the Western Front is due solely to the fact that they have been beaten. The Germans have 147 divisions on the Eastern Front. They could safely withdraw from 15 to 20 divisions from the Eastern Front to aid their forces on the Western Front. Yet they have not done so, nor are they doing so. They are fighting desperately against the Russians for Zemlenice, an obscure station in Czechoslovakia, which they need just as much as a dead man needs a poultice, but they surrender without any resistance such important towns in the heart of Germany as Osnabrück, Mannheim and Kassel. You will admit that this behaviour on the part of the Germans is more than strange and unaccountable.

Omitting diplomatical politesses, it's a direct accusation of betrayal on the reason of not fighting against common enemy.

Stalin was working with premises that seem odd to us

As others have said, in the Soviet view, the US/UK and Nazi Germany were not that different. They were enemies of Communism, and it seemed natural to Stalin that they would ally against the USSR.

Also, while Stalin's and Hitler's forms of dictatorship don't seem very different to us, to both Stalin and Hitler, they were opposites.

Stalin's preferred strategy up to the Nazi invasion of the USSR was for the western powers and the Axis to wear each other down as much as possible. The USSR would chose its moment to enter the war, and dominate Europe afterwards. This strategy conformed to Marxist-Leninist ideas about the inevitable course of history; Stalin's lack of immediate response to the invasion may have been partly due to shock that the impossible had happened.

US/UK fears of a separate peace

The Soviet pre-invasion strategy wasn't exactly secret, because it was so obvious. After the invasion, the US and UK fully expected the USSR to collapse, just as the Nazi leadership did. It wasn't until late 1941 that it became clear a collapse wasn't going to happen, and even then, some people expected it in 1942. It wasn't until after Stalingrad that it was clear that Germany couldn't defeat the USSR with the means it had.

Even then, there were fears that Stalin would make a peace that restored his 1941 borders. If he did that, he could revert to his pre-war strategy, allowing the US/UK and Germany to inflict losses on each other, and then stepping in at the right moment. There had been several sets of contacts, offering Germany progressively worse terms, but Hitler was never interested - he saw the USSR as his fundamental enemy.

Stalin's fears of a separate peace

It always seemed logical to him that the US/UK would combine with Germany against the USSR, and that they would be fools not to do it soon.

Hitler's hopes for a separate peace

The drowning man clings to straws... He was never interested in peace with the USSR, but hoped for the US/UK to join him against Stalin. Never going to happen. They'd made up their minds that Germany would have to be remade, to avoid all this happening again in a few decades.

The Japanese kept trying to get Hitler and Stalin to make peace

Addendum: The Japanese were at no point keen on going to war with the USSR. They'd tried that in 1932-39 and weren't interested in trying again, hence their neutrality pact. They wanted Germany and the USSR to be at peace, so that they could access German industrial production via the Trans-Siberian Railroad. To this end, they kept offering to mediate between the sides, having diplomatic relations with both of them.

Now, this was never going to get anywhere, because Hitler was absolutely set on destroying the USSR. The fact that the Japanese kept trying illustrates what a lose and uncoordinated alliance the Axis was - Germany and Japan weren't honest with each other about their war aims - and how little they understood Hitler. But the fact that they kept trying would have leaked, and created uncertainty for the Western Allies about Stalin's intentions.

Source: Germany and the Second World War, volume VI/I, The Global War, pp100-109 and 161-184.

I am sorry, but as a German I must dismiss your precondition that "the Germans" hoped for a separate peace. To the best of my knowledge the Germans were in general not aware of that idea because it sounds ridiculous.

Hitler had the ideological view of Lebensraum in the East, the submission of the Slavs and the enemy image of Bolshevism. There were several attempts by Stalin himself (1941), Japan (1942) and Italy (since 1942) to have a peace agreement with the SU. Hitler never wavered in his decision to continue the attack for purely ideological reasons (Visions of Victory: The Hopes of Eight World War II Leaders - Gerhard L. Weinberg).

Hitler on the other hand offered peace several times to England. Churchill not only declined, he insisted on his partners that they would not budge to any attempts of Hitler to settle an armistice. His hatred of Hitler was so great that after the attack of the Soviet Union, he famously stated: "If Hitler invaded Hell, I would at least make a favourable reference to the Devil in the House of Commons". And Churchill did not like communism at all.

The Germans were aware of this and they knew as long as Churchill was Premier, a separate peace was never an option. That was the situation. And for your information, the direct involvement of the US would not have been necessary. After 1941 the Britons gained the upper hand on the sea, after 1943 the Soviets gained the upper hand on land.

After the defeat was foreseeable, Germans were stunned and aghast. They had lost the first World War (there was also the idea that Germany could negotiate a Siegfrieden, a positive outcome of the war with the Western Allies. Have a guess what really happened and how likely a "separate peace" was in this light) and suffered under the reparations. Now they have risen again, were getting more and more powerful and then they lose everything. The heavy bombardment of cities (Hamburg and Dresden) with the severe civilian casualties gave the Germans the impression that destruction of Germany was imminent (see Morgenthau plan). The overwhelming thought of the Germans in this period was "What will happen to us ?", not clutching straws with a hope of a "separate peace".

Himmler tried to save his own neck by trying to get an alliance against the Soviets, nothing more.

ADDITION: I think we have the case that people tries to judge events from an Allied view and assign importance to things which are from a German viewpoint not important at all. The same applies for Germans thinking "X happened, so the Britons/Americans must have planned this" while in fact the Americans/Britons had completely other ideas.

The England negotiations were serious attempts of the Nazi Regime. All knew that after France's defeat and a mollified SU there was only one power left (The US was already raising eyebrows, but was still very inactive) which could threaten Nazi Germany. The naval blockade was a serious threat (very bad memories in WW I; Western and Middle Europe have scarce natural resources) and the impending war with the SU had another very good reason besides ideological grounds: With the vast natural resources of the SU a blockade against Nazi Germany would have been useless. So intense attempts were made (The Heß case itself was controversial in Germany; Hitler threw convincingly a fit and a (forbidden) joke was "Brown budgie flewn away. Please return to Reich chancellor's office."). But this happened all before the invasion of the SU and the huge advantage that a peace with GB offered meant that the Germans really believed that further negotiations were fruitless.

The question if peace with Churchill was possible definitely ended after Canaris asked 1943 what the conditions were if the Germans get rid of Hitler (which was really a new bargain). Churchill's reply "Unconditional surrender"...well, what do you answer ?

If you take a deep look at all the others mentioned (Jodl, Dönitz and the SS officers) you will notice how late those alleged hopes of "separate peace" occur. From a German perspective you go for peace if you still have bargaining power which Germany did not have anymore after mid-1944. The Battle of the Bulge was pure desperation. So, those offers were in fact begging for mercy when you know it's over, but the officer's code of behavior forbids to show weakness.

And what should one think of the House of Brandenburg miracle from a German perspective ? Sorry, but I and likely other Germans see it as unimportant, it is whistling in the dark when you already know it is over. On beginning of April when the story takes place the situation was completely hopeless: The Allied force crossed the Rhine and moved fast to the East, the Soviets had encircled Berlin and outnumbered German forces heavily, the cities were rubble and resistance completely broken. Think: Would a man seriously considering a wonder shoot himself in the mouth ?

My father served on the Eastern Front from 1943-45, as a non-commissioned officer for one of the Axis minor allies. He had at least heard rumors of a plan to surrender to the Western Allies, who would then unite with Germany to drive the Red Army out of Europe.

It is a fact that the Western Allies were not going to go for such a plan, but it is indicative of the mood in central Europe that the idea circulated. The Germans east of the Elbe knew what was coming:

Defeat was similarly inconceivable to men returning from the East, who chilled their compatriots' spines with phrases full of warning innuendo: "If you had seen what we saw, you'd know we mustn't lose the war." -- Grunberger, The 12-Year Reich: A Social History of Nazi Germany 1933-1945 (1971), pp. 41-42.

In addition, the tales of the First World War were well known. On the Eastern Front, both sides had been remorseless against unfriendly civilians.

All through 1944, the Germans saw the newsreels of the Eastern Front. They knew the geography and could see the Russians advancing further and further west. As defeat became certain and faith in Hitler broke down, some degree of hysteria set in and people began grasping at straws. Any rumor, no matter how wild and implausible, that offered an alternative to inundation, mass reprisals and destruction was seized upon.

In 1941, future President Harry Truman reportedly advocated a "bait and bleed" strategy that, "If we see that Germany is winning we ought to help Russia, and if Russia is winning we ought to help Germany, and that way let them kill as many as possible."

General George Patton suggested re-arming 26 German divisions and working with them to kick back the Soviet armies toward the Soviet border.

These views were not "official" U.S. policy, but in fact were held by officials that were high-ranking enough to lead people to believe that it could become U.S. policy.

I think you answered your own question.

The Western Allies indeed never wavered from the doctrine of "unconditional surrender".

However, some Germans did try for a separate peace and those attempts were sufficiently worrisome for the SU - even though they were soundly rebuffed both times:

1. Canaris 1943:

In 1943, while in occupied France, Canaris is said to have made contact with British agents.... Canaris wanted to know the terms for peace if Germany got rid of Hitler. Churchill's reply, sent to him two weeks later, was simple: "Unconditional surrender".

2. Himmler 1945 - did not even manage to contact a Brit or a Yank; his few contacts were Swedes and all they did was

asked Himmler to put his proposal in writing, and Himmler obliged

The logic is simple and natural:

Himmler: if I don't try, there is a certainty that I will be hanged. If I try, I might have a chance.

Stalin: Himmler is trying to make peace, there must be someone who he is talking to. Additionally, "we know" that the Germans are more eager to surrender to the Americans than to us. Treachery!!!

Note that the only treaty that Stalin signed but did not violate himself was the non-aggression pact with Hitler; this attitude towards international relationship does not lead to much trust (a swindler thinks that everyone is a swindler).

See also "Stalin and the Prospects of a Separate Peace in World War II": there are strong indicators that the lull between Kharkov and Kursk in 1943 was the time when Stalin tried to make a deal with Hitler. Stalin's Wars: From World War to Cold War also claims that Stalin proposed joining the Axis and exterminating the Jews in early 1942.

Later addition:

There is also an interesting 1944-03-20 memorandum from Donovan to FDR, describing an interaction in Sweden in Fall 1943 between an "Abram Hewitt" and Dr Kersten, Himmler's personal physical therapist, and Colonel Schellenberg, SD chief, from which we learn that

• Russians tried to make a deal in May 1943 but their proposal was not generous enough for Hitler and Himmler (but acceptable to Goebbels and Ribbentrop)
• Himmler wants to make a deal with either Russians or (preferably) the West, and wants the US to send a rep him (the request that Donovan ignored without even consulting the President)

One intriguing use of the term "blowback" I've seen was from Bob Woodward's book Veil. In propaganda terms, he used it to indicate a situation where lies told to further US interests "blew back" into US intelligence gathering, causing the US to believe their own lies. When that happens you think you know the truth when you actually do not, which can lead to persistently making horrible decisions.

Once you understand the concept, you start to see examples of it all over the place. This is in fact what I believe happened here. The Nazis and the Soviets under Stalin were mortal enemies, but they had one big thing in common: they both relied extensively on propaganda to define their world view.

In the Nazi case, they believed in the inherent superiority of "the Aryan race", and felt that the English and the Americans, as mostly fellow Aryans, were natural Nazi allies, and would come around to the inevitable logic behind the Nazi world view once there was no longer really anything tangible for them to fight for. They certainly ought to be persuadable out of sending their own to die saving a bunch of Jewish-led Slavs, if only someone could sit down and explain the situation to them from the proper (Nazi) point of view. Hitler's second-in-command even attempted to do this, and the above appeared to be his exact thinking.

In the Soviet case, an inherent part of their ideology was that the Capitalist powers (and foremost among those were certainly Great Britain and the United States) were doomed in the long run to their own Communist overthrow, and were thus dead-set on the destruction of the Soviet system. Merits aside, this kind of belief in an ongoing imminent attack from the outside is always very useful for reducing internal dissension, so its very common to find in authoritarian societies. The problem is if decision makers actually believe stuff that they just made up themselves, then they are apt to make some disastrously wrong decisions outside of their propaganda bubble. In this case, for anyone taking the Stalinist view as gospel it would be very tough not to believe that the US and UK would look to screw them over at the first instant possible.

If they were looking specifically for supporting material for this view it was certainly not wanting. A couple of decades earlier, both countries had supported the anti-soviet forces in the Russian Civil War. Poland and France had refused any Soviet military help whatsoever in the runnup to WWII, which is what drove them to attempt their own separate peace. To cap it, the western allies seemed to be dragging their feet in starting a true Western front in Europe, while Soviet forces were dying in the millions. There were also anti-soviet comments aplenty from Churchill and FDR one could point to if wanting to seriously bolster this case.

So basically the miscalculation in both countries had the same source, and the same source of most of the great miscalculations of history: believing their own lies.