The Volunteer by Jack Fairweather (W H Allen, £20)

You will undoubtedly know about Auschwitz and may well have visited the site of the most barbarous mass murders in human history.

It was here, deep in the Polish countryside a little over an hour from Krakow by a little town known locally for centuries as Oświęcim, that the Nazis in 1940 set up a camp to house Polish political prisoners. 

The camp was soon expanded to become the reception centre for slave labour from throughout the expanding Reich and, after the construction of an adjacent facility at nearby Birkenau, a place in which to concentrate, accommodate, kill and then dispose of ever-greater numbers of men, women and children —most but not all of them Jewish — from across Nazi Europe.

As countless works of subsequent scholarship have testified, Auschwitz lay at the very core of what came to be called the Holocaust. 

Yet we are only just finding out, thanks to former war reporter Jack Fairweather, about Witold Pilecki, a brave young Polish patriot and devout Catholic, who saw and reported on all this from the inside.

When Hitler invaded Poland at the beginning of September 1939, Pilecki took up arms to resist the advancing troops, only to be shocked shortly afterwards by the sudden advance from the east by the Soviet army and the collapse of the Polish capital, Warsaw.

What was a patriotic Pole to do as he saw his beloved nation caught between the two foreign evils of Nazism and Communism? 

Witold helped to found a secret resistance movement against the Germans, in due course agreeing to let himself become arrested and taken as a prisoner to Auschwitz. Once there, his mission was to write, and smuggle out, via a network of undercover contacts, detailed descriptions of the horrors going on inside the camp with the ultimately vain hope of arousing the western Allies into destroying this pit of evil.

If Witold himself were killed, whether by the Germans or by an Allied bombing raid on Auschwitz, he felt it would have been in pursuit of a morally honourable cause.

In fact, Witold survived Auschwitz, and the war — only to be executed for “treason” in 1948 following a Stalinist show trial in newly communist Poland. This is the harrowing tale told by Jack Fairweather. 

The Volunteer is a hugely impressive work and a highly unusual one. Fairweather has the rare gift of describing vividly the daily, mounting horrors of Auschwitz while also managing to encase this appalling story firmly within its widest historical perspective.

He also writes with the élan of a first-class novelist: Agatha Christie, when Pilecki and his fellow Auschwitz plotters plan an uprising or an escape, or Thomas Hardy, as we spot the Vistula or the nearby forest-lands at dusk or dawn. 

Above all, Fairweather presents in minute and impeccably sourced detail a portrait of a hitherto little-known yet heroic individual whose courageous contribution to the history of the war is now at last firmly on the record. 

Daniel Snowman’s books include ‘The Hitler Émigrés: The Cultural Impact on Britain of Refugees from Nazism’