At a time when millions of people were desperately trying to get out, a former soldier has described why he felt the need to smuggle himself into Auschwitz and ultimately save the life of a Jewish prisoner.
"It was evil, it bred evil," 92-year-old Denis Avey said. "So much so that even nature turned its back on this place.
"The bestiality in Auschwitz was something you couldn't ever believe could be."
Mr Avey was in his early twenties and serving in the British army when he was wounded and captured while attacking Rommel's forces near Tobruk, Libya.
He ended up being held at a German camp called E715, right on the periphery of a huge chemical complex, with the Jewish camp a few hundred yards to one side and a Auschwitz-Birkenau a couple of miles in the other direction.
Mr Avey managed to exchange his uniform with that of a Dutch prisoner called Hans, shaved his head, blackened his face, and smuggled himself into Auschwitz on two separate occasions, sleeping in the camp overnight on both.
Speaking at the Holocaust Centre in Newark today, Mr Avey, who now lives in Bradwell, Derbyshire, said: "Nobody knew anything at all about the horrifying state of Auschwitz and, believe me, it was a place of evil. It was a desperate place.
"I didn't see a butterfly, a bird, a bee, or anything - everything had turned its back and I thought even the great architect had turned his back."
Mr Avey, who appears at least two decades younger than his distinguished 92 years, was inspired to witness first-hand the horrors of the now-notorious camp by other prisoners, whom he affectionately terms "stripeys".
He said: "Other stripeys had said 'For God's sake, when you get back to England tell your people about this bestiality and the way we're being treated'.
"That inspired me in thinking 'Well, if I've got to tell people' - conjecture is not in my vocabulary at all - 'I've got find out'.
"I knew exactly what was happening because of the ghastly stench from the crematorium ... and the civilians told us a lot about stripeys who were going into the gas chambers and then being cremated, hundreds at a time, and that was it, I wanted to see how they lived."
Once inside the camp, Mr Avey met a young Jewish prisoner called Ernst Lobethall who told him in a few furtive conversations, spoken away from the guards, that he had a sister who had escaped to England on the kindertransport.
Mr Avey managed to track her down in the Midlands - where she still lives, now in her eighties - and got her to send cigarettes to Mr Lobethall, which he was able to trade within the camp.
Unbeknown to Mr Avey, who started speaking about his experience in Auschwitz only around six years ago when he made an appearance on BBC Radio Derby for a slot on war pensions, Mr Lobethall survived because of those cigarettes and went on to live a long and happy life as a lawyer in America.
He found out about Mr Lobethall only a couple of years ago when former BBC Berlin correspondent Rob Broomby told him he had found Mr Lobethall's sister, Susana, as he was researching the book they were writing together, The Man Who Broke Into Auschwitz.
Sadly, Hans could not be traced and is believed to be dead.
But the news of Mr Lobethall's survival was met with great joy.
"I couldn't believe it, I thought he was dead," Mr Avey said. "He had had these cigarettes, and cigarettes were worth a king's ransom, believe me, and he was able to exchange it for food and built himself up tremendously.
"It was tremendous, I couldn't believe it at all."
Mr Broomby said cigarettes in Auschwitz were "currency" and, describing what Mr Lobethall did with those sent to him via Mr Avey, he said: "It was alarmingly simple. What he did was trade them to have his shoes resoled just ahead of the death march.
"You've got to remember, in the death march if you fell over you were shot and you died in the ice. Primo Levi said about his time in the camps 'Death starts with the shoes'. It's incredibly symbolic.
"He provided for himself, with the cigarettes as currency, the one thing that would give him the chance to survive that trial where so many others died."
The writing of Mr Avey's memoirs, he said, provided him with the catharsis he had not been able to experience for some 60 years.
It also gave those working with him the chance to witness first-hand the effect of the news about Mr Lobethall's survival.
"He was blown out of the water, he could not believe what he was hearing," Mr Broomby said.
"For us watching, it was one of the best journalistic moments of my life."
:: The Man Who Broke Into Auschwitz, published by Hodder and Stoughton, is on sale now, priced £20.Reuse content