When liberation came, it came quickly. One night in January 1945, as ten-year-old Eva Mozes Kor and her twin sister Miriam lay in their bunks at Auschwitz-Birkenau, they were suddenly awoken by a huge explosion.
Outside, the winter sky was red with flames.
The Nazis had blown up the crematoria where the bodies of hundreds of thousands of Jews had been burned, for fear that the approaching Soviet Army would discover them.
Facing the unknown: Children liberated from Auschwitz in 1945
Moments later, Eva and Miriam were forced by guards out of their barracks with all the other young twins in Birkenau and marched by the SS down the road to the main camp at Auschwitz, one-and-a-half miles away.
It was a miracle that any of them were alive, for all had been subject to Dr Mengele's evil medical experiments in 'hereditary biology'.
In one experiment, Eva had been injected with a disease that Mengele wanted to study. She had become extremely ill - but kept telling herself she must survive.
'If I had died, my twin sister Miriam would have been killed with an injection to the heart and then Mengele would have done the comparative autopsies,' she explained later.
Yet now Eva was enduring another nightmare as the twins were frog-marched towards the main Auschwitz camp in the dark, their gaunt expressions occasionally illuminated by the flames and flashes of the artillery of the Red Army.
Those children who could not continue were shot, their bodies left by the roadside.
Eva made it to Auschwitz. And it was there, shortly afterwards, that she realised her suffering might finally be over when one of the women in the barracks started shouting: 'We're free! We're free!'
Nightmare: One million Jews were killed at Auschwitz, but the Russian Army was largely indifferent to their suffering and keen to repress the horrors of the camp
Eva ran to the door of her hut, but could see nothing in the snow. Only after some minutes could she make out Red Army soldiers dressed in white camouflage coats.
'We ran up to them, and they gave us hugs, cookies and chocolates,' she remembers.
'Being so alone, a hug meant more than anybody could imagine because that replaced the human warmth we were starving for.
'We were not only starved for food but we were starved for human kindness, and the Soviet Army did provide some of that.'
For the several thousands of weakened, emaciated prisoners who had survived Auschwitz, the Red Army soldiers of the First Ukrainian Front who liberated the camp of death on January 27, 1945, were the first friendly faces they had seen for years.
Undoubtedly, it was a moment for celebration.
Just as the anniversary this week, 65 years on, is reason to rejoice that the unimaginable horror of Auschwitz and one of the darkest chapters in mankind's history had finally come to an end.
Yet while we acknowledge the liberation, we should also pause to consider what happened afterwards to those who survived the camp's appalling regime.
Notorious: People walk to a ceremony at the former Nazi death camp on Wednesday to mark 65 years since it was liberated
Although some Holocaust survivors truly found joy after being freed from Auschwitz, for many it was a very different story - and one that most definitely does not offer us a happy ending.
A story of abuse, rape, theft and terrible betrayal.
For a start, despite being friendly to the victims, the Russians were strangely unaffected by what they saw at Auschwitz.
Indeed, the liberation was hardly reported in the Soviet Press - on February 2, 1945, there was a small report in Pravda, but hardly the coverage you would imagine.
One reason is that many of the Soviet soldiers who first arrived at Auschwitz had themselves endured horrors beyond imagining on the Eastern Front.
'I had seen towns destroyed,' said Ivan Martynushkin, one of the liberating soldiers. 'I had seen the destruction of villages. I had seen the suffering of our own people.
'I had seen small children maimed. There was not one village which had not experienced this horror, this tragedy, these sufferings.'
To such soldiers, Auschwitz was just one more terrible sight in a war already overflowing with atrocity.
Another factor was that the Soviets wanted to make political capital out of the death camps.
Betrayal: The train tracks leading to Auschwitz. Many survivors endured arduous journeys home just find their houses had been occupied by Soviets
Their Marxist propaganda downplayed the suffering of the Jews - even though out of the 1,100,000 people killed at Auschwitz, 1,000,000 <cite>were Jews - in order to claim that the murder factory was an example of fascist capitalism's exploitation of expendable workers.
In Soviet minds, there was little suggestion that this was genocide, no real belief that the souls they had liberated deserved special sympathy.
After liberating Auschwitz, the Red Army marched on to attack Berlin and 'trap the fascist beast in his lair'.
And the survivors they had set free were left to find their own way home from the torment they had suffered in Poland.
This was a time when Eastern Europe was awash with the human debris of the war.
Millions of civilians were travelling - some to try to get home, others to escape from the brutal Soviet advance. And the newly liberated prisoners of Auschwitz joined that great river of humanity.
Two of them were Helena Citronova and her elder sister. Helena was a pretty young woman in her early 20s; her sister was ten years her senior - but looked almost old enough to be her mother.
Helena and her sister trudged the roads of Poland by day, trying to get home to Czechoslovakia, and then sheltered in hedgerows or barns at night.
Often, they would share whatever shelter they could find with other women, also newly freed from Nazi camps.
They soon discovered that, in the darkness, Red Army soldiers would search for women.
'They were drunk - totally drunk,' says Helena. 'They were wild animals.' Red Army soldiers looked 'for cute girls and raped them'.
'Like wild animals, they hunted for girls at night'
In order to try to escape the attentions of the Soviet soldiers, Helena would often hide, helped by her older sister who would make herself look as unattractive as possible.
As a result, it was the other women cowering alongside them who suffered.
And Helena was all too aware of exactly what was happening: 'I heard screaming until they were quiet and had no more strength left.
'There were cases where they were raped to death. They strangled them.
'I turned my head because I didn't want to see because I couldn't help them.
'I was afraid they would rape my sister and me. They were animals. No matter where we hid, they found our hiding places and raped some of my girlfriends.
'They did horrible things to them. Right up to the last minute we couldn't believe that we were still meant to survive.
' We thought if we didn't die of the Germans, we'd die of the Russians.'
One day, just weeks after she had been liberated from Auschwitz, and while she and her sister were still trying to make their way home, Helena managed to borrow a bicycle and went for a ride.
It was one of the first moments of joy she had felt for years.
With the sun on her back, the wind in her air and the fresh countryside around her, she finally felt free.
After she had ridden for a little while, she stopped by the side of the country road for a rest. Then she saw a Red Army soldier approaching on a motorbike.
The soldier stopped and looked at Helena, bright and pretty in front of him.
'He'd seen a young woman,' says Helena. 'He threw his motorcycle down and a terrible battle began.
'I don't know how I managed to get away from this cruel Russian soldier, this criminal. He hadn't had sex in a long time but he did not manage to rape me.
'I kicked and I bit and I screamed and he asked me all the time if I was German. I said: "No, I am Jewish from the camp."
'I showed him the number on my arm. And at that moment he recoiled. Maybe he himself was Jewish.
'I don't know what he was. He turned, stood up and ran.'
Helena and her sister finally managed to make it back to their home, and from there they emigrated to Israel, where at last they felt able to put their horrendous experiences at the hands of both the Nazis and the Red Army behind them.
The exact number of sexual attacks perpetrated by Soviet soldiers as they advanced through Germany, and then in the immediate aftermath of the war, will never be known, but the figure is certainly in the hundreds of thousands if not millions.
The revelation that women who had already endured so much mistreatment in camps such as Auschwitz were then subsequently raped by their liberators adds a grotesque level of nausea to the story that did not exist before.
Auschwitz prisoners, like Linda Breder, say - incredibly - that they found their homecoming even more appalling than their time in the camp.
Like many of the other liberated Auschwitz prisoners, Linda was wandering through Poland in the late spring and early summer of 1945 trying to make her way home.
On the road, she and a group of other women accepted a lift in a truck from Soviet soldiers.
'They didn't want us to come back, they didn't want to have to settle their accounts with us and look us in the eye'
They did this only because they were so tired they felt they couldn't carry on walking - but still they were afraid, because they were well aware that the Soviets 'often raped girls'.
After a few miles the truck stopped. The women were ordered to get down from the back.
They were terrified, thinking they would all be raped. But the soldiers had another crime on their minds that day, and decided instead to rob them of everything they had.
This was bad enough, but, as Linda Breder said, 'at least we escaped with our lives'.
Worse was to follow for Linda when she finally made it back to her home town of Stropkov in Slovakia. She walked down her old street and knocked on the door of her house.
'The door was opened by a Russian or Ukrainian man,' she says. He was a complete stranger, and yet he was living in her house.
'Go back to where you came from,' he said, and then slammed the door in her face.
With the Soviets now occupying Slovakia, Linda felt that she had no hope of recovering her past life.
She had been sustained through her time in Auschwitz by the belief that, one day, she could go home and rebuild her shattered existence. That hope was now destroyed.
She turned down the main street of her home town and realised the houses that had previously belonged to friends and relations were now occupied by people from the Soviet Union. Only the non-Jews remained.
'When I looked into the windows of those houses, I had a feeling that all eyes were gazing at me.
'Everyone was keeping their distance as if I was poisoned or something. I left the next day and never went back. Going back was my worst experience. It was really catastrophic.'
And it wasn't just prisoners from Auschwitz who suffered on their release in 1945.
Walter Fried was an Eastern European Jew who had been forced to work in a Nazi labour camp.
After liberation, he went back home, together with his father, to the town of Topolcany in Slovakia, where they discovered that their successful family-run restaurant business had now been 'nationalised' and given to someone else to manage.
But Walter's father knew that all was not completely lost. Because before he and his son had been taken away by the Nazis, they had given their most valuable possessions to good friends - Christians - for safekeeping.
Now Walter's father visited them, saying: 'We left a little package with you, and you know exactly what the package contained - there was gold, diamonds and money.'
But the friends had a different recollection. 'Ah,' they said in reply, 'all you left was a few clothes.'
'We gave you gold and diamonds!' said Walter's father, in despair. But it was useless; they never recovered their valuables.
'We lost our last element of hope,' says Walter Fried, 'that the good Christian, who used to be a friend of the Jew, someone the Jew supported all the time - who used to be given food when he didn't have any money when he came to our restaurant - would respond like this.
'They didn't want us to come back, they didn't want to have to settle their accounts with us and look us in the eye. Our best friends from before became our worst enemies.
'In 1945, we were more threatened than in 1942 when we left. That's how much hatred there was.'
But it was not just the Jews. Perhaps the worst treatment after liberation was inflicted by the Red Army on their own compatriots.
Stalin had decreed there were no Soviet prisoners of war held by Germans, only 'betrayers of the motherland'.
This attitude could not have been expressed with more clarity than when units of the Red Army arrived at the concentration camp in southern Poland where Tatiana Nanieva was held.
Captured in 1942, when the hospital in which she worked had been encircled, she endured 2 1/2 years of imprisonment and in the process had to witness fellow Soviet prisoners being raped by Germans.
Then, in January 1945, she heard soldiers of the Red Army arriving, patriotic songs with their heads held high.
'Our feelings were joyful, elated,' she said. 'We believed normal life would begin again. I was yearning for my family.'
But the joy of liberation turned to despair as two Red Army officers approached her, one of them obviously drunk.
'So how did you live it up here? You whores!' he shouted. Tatiana felt her world collapse as he stood swaying, reaching for his pistol.
She ran, and managed to hide until the soldiers had sobered up. But whether they were drunk or sober, the charge against her was still clear: 'Betrayal of the motherland.'
For the 'crime' of allowing herself to be captured by the Germans, she was sentenced to six years in a Gulag and a lifetime's exile in Siberia.
No one has ever made a comprehensive study of the fate of all the survivors of Auschwitz and other camps who were then released into the maelstrom of Eastern Europe in 1945.
Certainly, there will be some happy stories among them.
But the overwhelming feeling among many of those who were liberated is one of betrayal and crushed dreams of freedom and happiness.
• LAURENCE REES wrote Auschwitz: The Nazis And The Final Solution, and wrote and produced the BBC TV documentary series of the same name.
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