If you want to exclude Flanders, my best guess would be somewhere during the second half of the 19th century up to the first half of the 20th century. Before that period, there would be no reason to not take (at least part of) Flanders. After that period annexing part of another country is a big nono for western countries.At what point (or war) could France have taken the french speaking netherlands? The area is rich in resources and is one of the birthplaces of the industrial age. If the area is part of France, what can we expect to change?
Possible, but the border would probably be to the north of the Walloon and Flanders border. Basicly Brussels, Louvain and south to France, Ghent, Antwerp, Bruges and north to the Netherlands.Perhaps a north-south partition of the Hapsburg Netherlands between the Dutch Republic and France?
The issue is that a large part of Wallonia was HRE, so hard to achive an annexion before the Republican/Napoleonic era. Maybe you could try to have the 1st Republic not giving it back to Austria, so that at Vienna it is not taken away given it was not an imperial conquest ? Or just Flanders is stripped from France and given to the Dutch to prevent France from getting Oostend and Antwerpen, but "useless" Walloonia remains French.
Or you get France to conquer the Prince-Bishopric of Liege and the Spanish possessions in Wallonia during one of the Renaissance War ?
Wallonia being part of the HRE should not be a problem. Flanders (as in the county, not all of the Dutch speaking part of Belgium) used to be French, just like Artois was. Charles V made it part of the HRE in a treaty with France and when France conquered. Artois and Dunkirk it stopped being part of the HRE and became part of FranceThe First Republic didn’t give it back to Austria. On the contrary Austria gave it to France in the treaty of Campo Formio and this was confirmed at Amiens.
Possible, but the border would probably be to the north of the Walloon and Flanders border. Basicly Brussels, Louvain and south to France, Ghent, Antwerp, Bruges and north to the Netherlands.
The thing is that before the age of nationalism there was no distinction between Wallonia and Flanders. France did not care that the Flemish spoke a different language, lots of parts of France did. France wanted all of the southern Netherlands and Flanders was worth more than Wallonia, because Flanders was richer and had a coast. So up till the age of nationalism there was no need to split "Belgium" along the language border. Only in the age of nationalism the distinction would be made and even then I suspect France wanted all of it. France wanted Luxemburg after all and (most of) Luxemburg spoke German (or a German dialect, or a language close to German, take your pick). So if you want France to just absorb Wallonia, you have to have a good POD. You probably need a war in the late 19th/early 20th century in which France and the Netherlands are aligned and oppose Belgium and win after which they decide to devide Belgium between them. So it must be a pretty harsh war, or Belgium must misbehave very badly (and no the Congo is not enough), for it to get disolved.
If you simply want Wallonia to be part of France and you don't care if there are parts of Flanders attached to it, have France be more succesful during the 17th, 18th or 19th century and you have a French Wallonia. It is a bit harder than just that. Besides militairy succes, France also needs diplomatic succes (or else you simply get a big alliance that will try to take it away from France or prevent France from getting "Belgium" like OTL), but it is possible.
At what point (or war) could France have taken the french speaking netherlands? The area is rich in resources and is one of the birthplaces of the industrial age. If the area is part of France, what can we expect to change?
True, but the border was not the language border. Flemish/Dutch speaking cities like Brussels, Louvain and Dunkirk would end up French.I've read that France and the Dutch Republic discussed partitioning the Spanish Netherlands during the Thirty Years' War.