I'm back, but I'm pretty fried, so all you're getting is a link to a Language Log post about Bastille Day and the languages of France and a quote from it:
From a linguistic point of view, however, the French Revolution was a disaster. The monarchy had been largely unconcerned with what languages its subjects spoke. At the time, the languages spoken by natives of France included six Romance languages: French, Occitan, Franco-Provencal, Walloon, Catalan, and Corsican (a dialect of Italian), the Germanic languages Flemish and German, the Celtic language Breton, and Basque. Some of these, especially French and Occitan, each had numerous divergent forms. Additional languages, such as Berber and Tahitian, now qualify as "French". A full list may be found in the Cerquiglini report Les Langues de la France.
One of the effects of the Revolution was to bring about a greatly increased centralization of the French government and a policy of establishing a standard form of French as the only language of the Republic. I emphasize that the policy adopted was not merely to ensure that all French citizens shared a common language, but to eliminate all competitors. This is readily seen in the title of the report by the Abbé Grégoire establishing the policy: Rapport sur la nécessité et les moyens d'anéantir les patois et d'universaliser la langue française "Report on the necessity and means of annihlating the dialects and of making the French Language universal". Since the Revolution, all French governments have been hostile to minority languages.