 On 1 September 1939, in coordination with the Soviet Union, Hitler ordered the German armed forces to invade Poland.It was on this day that Friedrich Kellner began to record his observations in a secret diary that he entitled "Mein Widerstand", "My Opposition".He wanted the coming generations to know how easily young democracies could turn into dictatorships, and how people were too willing to believe propaganda rather than resist tyranny and terrorism.