I was aware of the Franco-Prussian war
That actually kinda surprises me. Most French and German people I meet only know it in passing and Brits tend not too have heard of it at all so an American who knows about it is a rare treat indeed.

I was aware of the Franco-Prussian war, and that it had a real impact on the how and why of WW I, but I don't think it had the impact on that war that WW I had on the subsequent wars (WW II, Korea, and Vietnam). There is always a continuum, because people beget people, and ideas beget ideas, but I think that some wars are tied very tightly together, while others are not so much.
I guess it's all shades of grey really. I'd agree that the link from WW1 to WW2, for example, is far stronger than the Franco-Prussian to WW1 link but I'd still call FP to WW1 pretty causal. It led to the formation of Germany for a start.

The link I made between the Napoleonic conflicts and the Franco Prussian war was probably alot more tenuous.

The really interesting bit, though, was that the Franco Prussian war was largely a result of French fears about German status overtaking their own, which is exactly the same reason why they wanted the Euro and a federalised Europe. In fact pretty much every European war since 1815 onwards has been about the French and Germans vying for position. That's still going on only now the conflict's economic rather than military. And round and round we go...