When I traveled to Auschwitz a few years ago, one question played over and over in my mind: Did they know? Did the German people know what was happening in this camp near their own border, in their own occupied territories? With the trains coming and going year after year, with the long lines of prisoners and the billowing smokestacks, did they just turn a blind eye to the atrocities? Had they become desensitized to the point that they could no longer see the carefully choreographed death operations nearby? Some concentration camps, like the one in Dachau, were set in...