On January 1, 1957, the Saarland officially rejoined the Federal Republic of Germany, ending a decade of French economic and political administration. A 1955 referendum had seen Saarlanders overwhelmingly reject a proposed 'Europeanized' status, choosing reunification with Germany instead—a peaceful territorial resolution rare in postwar Europe.
The Saar, a coal-and-steel-rich sliver of land on the French-German border, had changed hands so many times in the twentieth century that its inhabitants had reason to feel like a bargaining chip rather than a nation. France separated it from Germany after both world wars, hoping to annex its industrial capacity permanently, and after 1945 administered it as a nominally autonomous protectorate closely tied to the French economy and currency.
In October 1955, France tried to settle the question through diplomacy dressed as democracy: a referendum offering Saarlanders a 'European Statute' that would keep the territory outside both French and German sovereignty, administered instead by the fledgling Western European Union. Voters rejected it decisively, by roughly two-to-one, in what was widely understood as a vote for German reunification rather than European experimentation.
Negotiations followed, and on January 1, 1957, the Saar was politically reincorporated into West Germany; economic union followed on July 6, 1959, when the Deutsche Mark replaced the franc. The episode stands as one of the few twentieth-century border disputes in Western Europe resolved through referendum rather than force, a quiet vindication of self-determination amid the wreckage of two world wars.