What is "rattachism"

Rattachism or Reunionism (Réunionisme) is minor political ideology which calls for the French-speaking Belgium or Wallonia to secede from the Belgian nation-state and become part of France. Brussels, which is majority French-speaking but located in Flanders, may be included within this ideology as may the six Flemish municipalities with language facilities for French-speakers. It can be considered a French-speaking equivalent of Orangism or Grootneerlandisme in Flanders.

The Rattachist ideology is associated with a faction of the Walloon Movement and is advocated by the political parties Walloon Rally and Wallonia-France Rally. Neither party has ever gained parliamentary seats.