From Orderly and Humane: The Expulsion of the Germans after the Second World War, by R. M. Douglas (Yale U. Press, 2012), Kindle pp. 69-70:
Even after the return of peace [in 1918], national governments would pioneer methods of displacing unwanted minorities that would be applied on a much larger scale twenty years later. A case in point was France’s “cleansing” (épuration) of the border provinces of Alsace and Lorraine between 1918 and 1921, in what Mark Mazower describes as “a blatantly racist assault on the civil rights of Germanspeakers” in the region. After his victory in the Franco-Prussian War of 1870, Bismarck had ill-advisedly annexed the ethnically mixed provinces to the Reich, creating a permanent antagonism between the two countries. When France reconquered Alsace-Lorraine in 1918, it immediately set out to eliminate any basis for future disputes about the provinces’ political complexion by purging them of those who might be thought to favor their reincorporation into Germany. To facilitate the process, the population was divided into four categories by the end of December 1918. Residents whose French loyalties were unquestioned were given identity cards marked with the letter “A,” signifying that they had been citizens of France before the Franco-Prussian War. Those who had at least one pre-1870 French parent received “B” cards. Citizens of Allied and neutral countries were placed in the “C” category; the remainder—a total of 513,000 “enemy” nationals and their children, including those who had been born in Alsace-Lorraine—became members of the “D” class. As we have seen, Heinrich Himmler’s racial gurus would use this system as a model when devising the Deutsche Volksliste in occupied Poland two decades later.
Like the Volksliste, the French classification scheme could readily be applied for the purpose of discrimination as well as expulsion. Category “A” card-holders, for example, could exchange Reichsmarks for francs at a much more favorable exchange rate than members of the other classes. Holders of “B” cards were often turned down for public-sector jobs on the ground of their mixed parentage. The most stringent disabilities, needless to say, applied to the “D” class, whose members among other restrictions were not permitted to travel. Petty persecution, however, soon gave way to deportation. The first to be removed were German-speaking civil servants; later, those marked for expulsion included factory owners and the unemployed. Their fate was determined by commissions de triage that held meetings in camera to assess the French patriotism of the persons concerned, often on the basis of denunciations solicited by local officials from individuals waging personal vendettas. Those who failed this examination were pushed across the frontier into Germany. They were permitted to take thirty kilograms of baggage with them and a maximum of two thousand Reichsmarks, all their remaining property being forfeited to the French state. But an even larger number were induced to opt for “voluntary repatriation” on the same terms. They did so because they expected to be removed eventually; because life in the “D” category had become intolerable; because, although not personally removable, their spouses or children were “D” card-holders; or, in some cases, because they feared physical attack by members of the majority population. Altogether, nearly 100,000 expellees and “voluntary repatriates” were transferred to Germany before the system was discontinued in July 1921.