The cold war began after wwII. It was an evil the culminated in the rise (and thankfully the fall of Senator Joseph McCarthy from Wisconsin). The fear was that Communism would replace the threat that Hitler represented. What made it so bad was that McCarthy disregarded all that was right and decent in America. The first amendment almost wound up in a discarded junk heap.
McCarthy accused everyone who came before him as a communist. There was a way of getting out of it. You could rat on someone else especially if McCarthy didn't know about the person you ratted on.
