If Hitler had not thrown the Communists into camps in 1933, there would have been civil war and bloodshed. The Communists would have revolted against the legally-elected government. The greatest danger of civil war in Germany came in 1932, when it was clearly a choice between Communism and National Socialism. So Paul von Hindenburg and the other conservative bourgeois elements chose Hitler. So did I, and I would do it again if a choice between Communism and Nazism arose.
To Leon Goldensohn, May 2, 1946, from "The Nuremberg Interviews" by Leon Goldensohn, Robert Gellately - History