To be honest I never considered the warm up. Kristallnacht was perhaps the best-known incident in a shameful period of German history, and one that none of us should forget.
In his thriller, Garden of Beasts, Jeffrey Deaver visits Berlin, 1936, and looks at some of the anti-Semitism (and the racial hatred that went beyond the Jews). It's an entertaining story but one that can bring that period to life.
My papa was one of the soldiers who broke into Germany and liberated a concentration camp that had no guards around but lots of starving Jews. I never thought my father was a very good father, but he was a hero in the second world war.