Via audio book, I've been reading the second volume of William Manchester's magisterial biography of Churchill, The Last Lion, (I finished the first volume a few weeks ago) and am thus working through the lead up to World War II.
There was an evocative little snippet that I heard the other day in which British Lord Halifax went on a diplomatic visit to Hitler's Berchtesgaden retreat in 1937 to discuss various issues. Over dinner, Halifax's tenure as Viceroy of India came up, and in reference to the then current troubles relating to the British rule there, Hitler advised that the solution was simple, "Shoot Gandhi!"
Manchester reports that Halifax took this as a joke, and related it to Prime Minister Neville Chamberlain on his return as such, to good effect. With the benefit of hindsight informing Hitler's character, it seems fairly clear that the suggestion was probably meant quite seriously -- though he may well have assumed that the British hadn't the stomach to follow through on such advice.
Whether in the civic or the personal sphere, basic guardrails of moral acceptability ("You just don't do that!") can seem like boundaries of reality -- until they aren't.