After the disastrous defeat of France, which ended the Franco-Prussian war of 1870-1871, the two belligerents signed the Treaty of Frankfurt on May 10, 1871. This treaty obliges France to yield to Alsace all Alsace (except the territory of Belfort) and part of Lorraine. A treaty clause requires Alsatians and Lorraine born in the annexed areas to choose between the two nationalities. Those who want to retain French nationality must then leave their homeland, now German. Out of 1,597,000 inhabitants, more than 450,000 will opt for French nationality. They leave their ancestral homeland and settle in Lorraine remained French, Paris region, Algeria, North America or South. It is a simple statement to the mayor that allows these optants to remain French. These nominative declarations will be published in the additional part of the Bulletin of laws - the forerunner of our Official Journal - of 1872.

• Bulletin of the Laws

Numerical nominative directory of over 380,000 Alsatians or Lorraine opting for French nationality in 1872.