How the SAS liberated Bergen-Belsen and discovered a Nazi-run hell

By the spring of 1945, the war in Europe was heading towards its bloody and violent close as Allied forces battled deep into Nazi Germany. At the vanguard of the advance were the battle-hardened soldiers of Britain's elite regiment, the Special Air Service.

Formed in the deserts of North Africa in July 1941 by David Stirling and Blair "Paddy" Mayne, the SAS had also fought across Italy and Nazi-occupied France with great distinction. But on April 8, 1945, the war's bloody endgame began as the Allies bludgeoned their way into Germany.

There, the SAS - moving at the spearhead - could no longer rely on the local population to assist them with shelter, food, intelligence and to fight alongside them.

In contrast to their operations behind the lines in France, no longer were they liberating a country from a hated force of occupation. Once they thrust into the Third Reich they were the invaders.

As the SAS advanced in their open-topped Willys Jeeps bristling with machine-guns, their Canadian comrades, who were sat atop their massive Sherman tanks, coined the phrase "Our little friends in their mechanised mess tins" to describe them.

What was to happen in the coming days would cause shockwaves around the world.

The fighting in Germany was suicidal, for Hitler had ordered the invaders repelled at all costs. But there was another more sinister reason why the Nazis were battling so hard. They were hiding a terrible secret - one that would cause untold revulsion around the world.

It was as the SAS approached the town of Celle, 155 miles inside Germany, that the darkness was about to descend. A series of partially blown bridges lay ahead, and only the SAS with their nimble jeeps could make it through.

A few days earlier Allied warplanes had raided Celle - some of the bombs falling upon key bridges. But others had hit a train crammed with thousands of concentration camp inmates. Hundreds had been killed but more had fled from the wreckage.

As the SAS reached Celle, they were about to encounter some of the survivors.

Captain Joe Patterson, an SAS medic, was approached by a concerned German citizen. He explained there were patients nearby in need of urgent medical attention. They were being held in a "Konzentrationslager", a concentration camp, he warned. To Patterson, as to all then present, the word had no special significance. Not yet anyway.

Patterson was led to a sinister-seeming enclosure. A German soldier was standing guard. After ordering him to open up, Patterson stepped through the gates. What he found shook him to the core. Inside was a scattering of filthy straw and, in among that, "half buried in the manure", he found scores of "creatures with life in them, not much, but a little.

"The staring eyes gleaming out of the slate skeletons made an impression it is impossible to describe. We were absolutely horrified. It was difficult to imagine that these had once been men."

As Patterson discovered, these were the survivors of that bombed-out train. They were awaiting their fate - to be "taken away to be gassed and shot".

Having checked over the barely living skeletal figures, Patterson loaded the worst aboard an ambulance and rushed them to Celle hospital. There, he ordered the German medical staff atgunpoint to save the newcomers' lives or die themselves.

But worse was to follow. On April 15, 80 years ago today, the SAS landed a new mission. Allied forces were having a "sticky time" on the approach to the village of Belsen, just to the north of Celle.

The SAS's order was to "carry out small task in concentration camp". As revealed in my book SAS Daggers Drawn, one of their own men, SAS Trooper Jenkinson, was being held captive in Belsen. The mission was to break him out. As their convoy of jeeps rumbled along a narrow rural lane, it was Lt John Randall, a man who'd served as Paddy Mayne's signaller, who rode in the lead vehicle. He spied a pair of odd-seeming gates to one side, which were standing wide open.

As the SAS would later report, the "little village of Belsen", which "had less than 100 inhabitants", lay in "one of the prettiest wooded areas", which "afforded ample seclusion for a concentration camp".

But right then there was nothing to suggest they were at the verge of hell.

As they turned through the gates, Randall detected there was something in the air - some tension, a spine-tingling malevolence - that put him on edge. The first manifestation of it was a group of watching SS men, but they showed little sign of having any fight left in them.

They were clearly guarding this facility, whatever it might be. The fences, rows of barbed wire and watch towers resembled a PoW camp.

After 30 or 40 yards, the SAS reached a fortified gatehouse. Beyond that layserried ranks of barrack-like huts - low-lying, made of rough, wooden planking and ugly.

As they slowed at the gatehouse, Randall became aware of an unsettling smell. At first it struck him as being sickly sweet, cloying. It made him want to gag. Finally it struck himwhat it was - the smell of putrid decay and death. And once smelled, it could never be forgotten.

As the jeep came to a halt, ghostly figures emerged. Hordes of them. A tide of wretched humanity washed around the jeep, most dressed in striped pyjama-like uniforms; all a deathly grey.

Some were clothed in rags. Yet more wore nothing - men, women and children utterly unconcerned at their nakedness. They resembled walking skeletons.

Their eyes were sunken pits, their cheeks hollow and cadaverous, their skin bleached yellow, as fragile as tissue paper. Hands reached out. Voices begged for food, for water, for help. There were no words for this.

The soldiers had stumbled upon some devilish manifestation of Hitler's Reich, "the likes of which the world had not even begun to imagine".

But, as they all had to remind themselves, these were actually human beings.

Standing in his jeep, Randall addressed the crowd. He was a British soldier, he announced, and there were more coming. They would bring help - food, medicines and freedom. Blasting the horn, they forced a passage through. They neared what they imagined to be a potato field. White objects jutted out of the earth. These, they realised, were human limbs - "arms, heads and legs locked in a sickening embrace of death".

Figures moved zombie-like, plucking an item of striped uniform here, a cap there, a pair of clogs from the feet of the dead. It was one of many mass graves.

A second jeep followed. At the wheel was SAS original Sgt Albert "Reg" Seekings. If looks could kill, those he threw at the SS guards would have "scythed all ofthem down".

Beside him was Captain John Tonkin, the patrol's long-experienced commander. The two men epitomised the bravery of the SAS. But it took a different kind of courage and willpower to get down from the jeeps to confront what was here.

As they dismounted, they had theirweapons gripped tightly. A group of German soldiers approached. At their centre was the camp commander, Josef Kramer. The SAS were face-to-face with the "Beast of Belsen', as he was known, plus Irma Grese, his sidekick dubbed the "Hyena of Auschwitz", for she had until recently worked at that concentration camp.

SAS original Johnny Cooper was there, too, aghast at what he was witnessing.

"We simply could not comprehend how it was possible for human beings to treat their fellows in such a brutal and heinous way... we found it difficult to keep control of ourselves," he recalled.

Reg Seekings was gripped by an "utter rage... on the verge of pulling out his pistol and shooting the first German guard he came across".

Kramer led them to a nearby hut. On the bunks the dead mingled with the living.

Reeling, Randall, Cooper, Seekings and Tonkin stumbled back into the light. Once outside, an even more enraging sight met their eyes. A camp guard was beating aprisoner with the butt of his rifle. Seekings was beside himself. He asked for permission to intervene.

Marching up to the SS thug, the Army boxing champion unleashed a powerful punch - the rage within him ensuring that one blow floored the guard.

He tried getting up again only to get more of the same. This time, wisely, the SS man stayed down.

Taking a grip on the shock and revulsion he was feeling, Tonkin ordered Kramer and Grese to be locked in the guardroom. He then gathered all the SS officers and lined them up.

"We are now in charge," he announced. "Any guard who attempts to treat a prisoner with brutality will be punished. Unless the shooting stops immediately, you are all going to die very horribly."

The shooting did stop. Right then, that kind of rough-and-ready justice was the only thing the SS would understand. With time, a greater justice - a proper reckoning - would follow.

Shortly, the SAS were relieved by advancing Allied troops, who would ensure that the key guilty parties would stand trial. As the SAS jeeps pulled away from the gates of Bergen-Belsen they had achieved their mission; trooper Jenkinson had been discovered and brought out alive.

But Johnny Cooper - just 21 - knew those scenes would "stay with me forever".

He, like so many, would be haunted. "As long as I live," Cooper would write, "I will never forget the Germans who perpetrated such acts."

In their wake, Patrick Gordon Walker of the BBC's European Service arrived. He would report how the former SS guards were forced to dig mass graves to bury the dead. Some fell exhausted into those pits - to be jeered at and spat on by those camp inmates with the strength to do so. Some guards committed suicide.

Walker ended his broadcast: "To you at home, this is one camp. There are many more. This is what you are fighting.

"None of this is propaganda. This is the plain and simple truth."

It was. Thanks to the SAS, finally the truth of the Nazi concentration camps had been revealed to the world.

• Damien Lewis is the author of SAS Daggers Drawn (Quercus, £22)