From Orderly and Humane: The Expulsion of the Germans after the Second World War, by R. M. Douglas (Yale U. Press, 2012), Kindle pp. 366-368:
The frequently reiterated assertion that the clearance of German populations from Poland, Czechoslovakia, and Hungary has in some way prevented the outbreak of World War III is a proposition so obviously false as hardly to deserve rebuttal. What made for peace in Europe was a lengthy occupation of Germany by both superpowers, which in itself offers a complete explanation of why, so long as it continued, no danger was to be apprehended from that quarter. The successful rehabilitation of the German political system, the inculcation of democratic habits and instincts among the people, and the binding together of postwar Germany within a larger European union are nearly as important factors in the transformation that has taken place in the character of European nationstate interactions since 1945. In these circumstances, the continuing presence of significant ethnic German minorities in Italy, Romania, Hungary, and Russia has not threatened the peace of the continent. There is no reason to suppose that if others had remained in their ancestral homelands a greater menace was to be apprehended.
Lastly, the suggestion that the ethnic Germans were, as presumed fifth columnists before the war or eager Nazi collaborators during it, especially if not uniquely deserving of punishment is no easier to sustain. As we have seen, a rule specifying a minority nationality’s unconditional duty of loyalty to a state to which it has been unwillingly attached that can be depended upon to vindicate the Czech or Slovak nation’s stance in 1918 [deserting in great numbers to fight for Russia rather than Austria-Hungary] and to condemn that of the Sudetendeutsche twenty years later is difficult to formulate. As for their wartime record, evidence is scanty that it was any worse than, or different from, that of the German people as a whole. Unquestionably that is quite bad enough, and I should not wish to be interpreted as contending otherwise. But even if all Germans, ethnic or Reich citizens, were equally guilty, not all Germans were equally severely punished. Why the Volksdeutsche, who if the worst that can be said about them is true came late to Nazism, should have been imprisoned, expropriated, and deported when the people of the country that originated Nazism and exported it abroad by the most brutal means suffered none of these things is hard to square with notions of strict and impartial justice.
More to the point, it conveniently elides the wartime record of the majority populations, which itself did not always bear close examination. Many Slovaks, for example, bore little less responsibility for the dissolution of Czechoslovakia after the Munich Conference than did the Sudeten Germans. For most of the Second World War, Slovakia was a German client state; Slovak troops took part in the invasion of Poland alongside their German allies in September 1939, and of the Soviet Union in June 1941. With only a single dissenting voice in the Slovak parliament, the great majority of the country’s Jewish population was expelled to German-controlled territory, from which only a comparative handful returned alive. Yet few Slovaks were punished after the war for these offenses, and none expelled. Besides, at a more mundane level the postwar meaning of “collaboration” was highly variable, with the same actions—or inactions—attracting either official toleration or condign penalties based on one’s ethnicity. During the Great War of 1914–18, J. R. Sanborn points out, some of the inhabitants of central and southeastern Europe “held affinities for one occupying force or another … but most people wisely tried to keep their heads down, to stay out of danger when they could, and, when all else failed, to run away. Nothing got you on the end of a rope faster than taking sides in a fluid war with an uncertain outcome.” In the Second World War also, this inglorious but time-tested formula for survival was the most popular strategy practiced by ethnic Germans, Czechs, Poles, Hungarians, and most other peoples who were given the opportunity to do so by their Nazi overlords, or, in eastern Poland between 1939 and 1941, their scarcely less vicious Stalinist counterparts. (Tragically, it was an option denied to Jews, Sinti, and Roma.) For only the Germans, though, was it adjudged a “passive war crime” at the end of the conflict.