All Rounder
Gone Fishin'
How big could France (not including colonies) get in Europe by the time 1939 rolls around?
This belongs in pre-1900, since any post-1900 POD France couldn't plausibly gain anything aside from the corner of Italy around Ventimiglia (for Central Powers Italy--France had a plan for annexing Ventimiglia after WWII) and of course France could possibly gain the Rhineland from Germany. And considering that a good deal of the Western Front of WWI was about preserving Belgian neutrality, I don't see France annexing them either, or Luxembourg, unless Luxembourg joins Germany for some reason before 1914. I definitely don't see France carving up Spain (wouldn't they just support the independence of those areas instead?)
Post-1900, all of them thus seem implausible besides Switzerland, where France had a war plan for invading the country, and possibly if they won the war still (invading Switzerland wouldn't be a good idea for France, I think), they could partition it with Italy on linguistic lines. Maybe Andorra could join France depending on how the Spanish Civil War goes? I don't know.
It realy depends on what POD you are using. I realy doubt that with a POD after 1900 it is possible for France to annex Belgium, the Netherlands, Switserland or parts of Spain. Even Luxemburg is unlikely. None of these countries want to become part of France (I think even Wallonia doesn't, at least not in the early 20th century) and I don't think France is able to conquer any of these countries. Well obviously France can attack and easily defeat the Luxemburgish army, but it won't be able to handle the international reaction. The best parts of French expansionism would be in Germany after defeating them in a war (like WWI). Unless France is incredibly stupid, I don't think either Luxemburg, Belgium or Switserland would join Germany so France would not be able to get any of their territory (and if they would have joined Germany through French incompetent diplomacy, WWI would be very different, partly because the French diplomatic status would be very different).How big could France (not including colonies) get in Europe by the time 1939 rolls around?
It realy depends on what POD you are using. I realy doubt that with a POD after 1900 it is possible for France to annex Belgium, the Netherlands, Switserland or parts of Spain. Even Luxemburg is unlikely. None of these countries want to become part of France (I think even Wallonia doesn't, at least not in the early 20th century) and I don't think France is able to conquer any of these countries. Well obviously France can attack and easily defeat the Luxemburgish army, but it won't be able to handle the international reaction. The best parts of French expansionism would be in Germany after defeating them in a war (like WWI). Unless France is incredibly stupid, I don't think either Luxemburg, Belgium or Switserland would join Germany so France would not be able to get any of their territory (and if they would have joined Germany through French incompetent diplomacy, WWI would be very different, partly because the French diplomatic status would be very different).
Simply put, I think that France with the Saar region (and perhaps a bit more of the German Rhineland) is the biggest France can get with a POD around 1900.