German communists during WW2?

I am following a seminar on "Europe Between the Wars" currently, and in relation to this got to wondering about the fate of German communists during the 2nd World War.

Obviously, many leading members either fled the country before the war (Walter Ulbricht etc.), or were removed by the Nazi regime (Ernst Thälmann etc.), but what about all the ordinary members (or voters) of the KPD?

Some of course fought in the Spanish Civil War, some ended up in the German resistance etc. But judging by the number of people who voted for the KPD during the years leading up to Hitlers takeover (13%-17%), the size of the electorate and the massive conscription that happened during the war, tens of thousands of communists (or communist sympathisers) must have ended up fighting for The Third Reich. Most of these on the Eastern Front against The Soviet Union.

This subject leads to many questions in my mind :

What is the psychological rational behind this - from the point of view of these people?
- Are people just following orders? Afraid to be prosecuted or worse?
- Does the urge to "defend" ones homeland triumph over ideology?
- Does comradeship and sense of obligation towards fellow soldiers triumph over ideology?

What were the personal feelings and experiences of these people?

Were there attempts towards defecting to The Soviet Union? Or any uprisings/rebellions?

Did the Wehrmacht (or the regime) take special care to disperse these people to as many different units as possible? Were they kept out of the army all together (as long as possible) and instead put to work in production etc.?

Does anyone know if there are any books/studies on this subject?

Well I must admit first that my information on the matter is quite limited.

I'd suspect people who voted for the leftist parties pro-nazism did it because they thought that they, with their promises of better living condition to the proletariat, would do the best for their voters. People are practically always selfish that is to be remembered. Germans were mostly pretty nationalistic at that era and it superseded and "internationalist" or "communist" doctrines they were told. I'd expect most of the left-wing supporters of Germany to have fought under the flag of Germany in WW2. Those who didn't either escaped or formed resistance groups.

Well, even if the german communist voters died during the war,purged by the nazis or fled the country, half of the germans lived under a communist regime for nearly a half-century.