As the title suggests, this scenario details the possibility of France becoming engulfed in a Civil War, or perhaps in something similar to the Paris Commune of 1871, in the wake of a defeat inflicted by the Central Powers following the Great War.
This is assuming a scenario in which the US did not become involved, Russia is in the midst of its own Civil War, and Germany, while victorious, has enough problems of its own sorting out the various ethnic struggles in Central Europe (like protecting its own ethnic minorities in countries on the brink of collapse like Austria-Hungary) to be able to intervene with an invasion (war ends at around 1917).
What sort of French state would emerge from this crisis?