We associate the Holocaust with Nazism, but forget that many of the killers were not even German; we think of concentration camps, yet many victims were murdered in towns and villages, fields and forests. Here a history professor at Yale University demonstrates how it was the invasions of Austria, Czechoslovakia, Poland and Russia that made the Holocaust possible; how the destruction of states and institutions created a lawless zone in which anything was permissible; and, chillingly, how it could happen again.