Now that I have been unconscionably flippant about the worst criminal act and human tragedy of the second millennium, let's return to the issue in all its severity.

Most of the concentration camps of Nazi Germany were labour camps attached to German industry, such as production sites for building materials like bricks, gravel, steel, armaments and other war products such as shoes made by the Bata shoe factory. Many evolved into extermination camps. By 1944, there were 385 concentration and extermination camps in total under the supervision of Heinrich Himmler.

Auschwitz-Birkenau, near Cracow in Poland, was initially a prisoner of war camp for Russian prisoners of the Eastern Front. But Himmler was an intelligent man, and he soon realized that his concentration of cheap, captive labour would be attractive to IG Farben, the third largest company in the world, and he arranged with them to build a factory to take advantage of it. It was never completed and instead the camp turned into the largest extermination camp of the war, with 1,250,000 deaths.

Only a few camps were founded purely as extermination sites for the Jews of Europe. They were:

Sobibor (Poland) 200,000 killed
Treblinka (Poland) 750,000 killed
Belzec (Poland) 550,000 killed, and
Kulmhof (Wartheland, now Poland) 150,000 killed.

The most infamous of the remaining camps were Dachau (near Munich), Bergen-Belsen, Sachsenhausen (in Oranienburg, a brickmaking centre near Berlin), Mauthausen (near Linz, Austria), Majdanek (near Lublin, Poland), Buchenwald (near Weimar), Gross-Rosen, Neuengamme (near Hamburg), Ravensbruck, and Lichtenburg (a women's camp between Bayreuth and Weimar).

My grandfather was in one of the British Army divisions that liberated Belsen.

For those whose families never actually suffered in the camps, the real horror of the Nazi crimes is that most of the people who committed them were just ordinary Joes doing their ordinary jobs. And if Joe next door is capable of such consummate evil, then maybe any of us are. In her famous articles in the New Yorker on the trial of Adolf Eichmann in Jerusalem, Hannah Arendt revealed that Eichmann was not a flamboyant mass murderer as everyone wanted to believe, nor the demonic monster of everyone's imagination: he was a bland functionary whose life consisted of pushing paper and carrying out the administrative drudgery of an ordinary bureaucracy. The primary difference is that his employer was in the business of exterminating people and he had no problem doing his job. She called it "the banality of evil."

Another author has written of the men who designed and built Auschwitz that none of them were born to be mass murderers: "They inched their way to iniquity."