While writing my WW2 spy story, The Black Orchestra, I had to research many details about the early years of the war. I had to find a map of Berlin for the period, and I found one here.
I had to find answers to 1001 questions, like these:
What food and drink did Berliners have access to?
Was coffee available?
When was food rationing brought in?
What about clothing rationing?
How widespread were telephones in Berlin?
Were the phones tapped by the Gestapo?
What about public phone boxes?
What levels of salaries/wages were people earning?
Details of public transport – buses and surface and underground railways
Details about railway stations
Were bicycles common?
Were domestic flights allowed?
What about international flights to neutral countries?
What did people wear?
Where were there open-air markets?
What was bought and sold on the black market?
What sort of cigarettes did people smoke?
Details about Wehrmacht and SS ranks.
Some of the questions I had to answer were more fundamental to the storyline:
What did ordinary Germans believe/feel about the Communist party “threat”?
What did ordinary Germans believe/feel about the so-called “Zionist threat” to the Reich?
What was people’s perception of Hitler? Of Reinhard Heydrich and the other nazi leaders?
Was membership of the nazi party mandatory for people in the public service?
What about members of the armed services?
What was the role of each of the various branches of the police, ORPO, KRIPO and Gestapo?
And the biggest question of them all:
What did the man in the street know about the nazi purges of the Jews in the early war years?
I decided, after much research, that the German people knew that the nazis were oppressing Jewish Germans – removing their basic rights (including their rights to earn a living), burning their businesses, and deporting them. But I don’t believe the German people knew of the nazis holocaust, not during the early years of the war, anyhow. The “final solution” was not proposed until the Wannsee Conference in January 1942, and it was only after that that the killings became systematic.