>>513387516
I'll keep this as brief as possible:
>Germany unifies and gives France a bloody nose in 1870s
>by early 1900 German economy produces more than Britain
>WW1 happens because Germany wins a contract to build a railway in Austro-Hungary (taking further market share from Britain, France is happy to fight Germans again)
>WW1 ends in Germany being forced to pay reparations to France in Gold
>simultaneously Germany is barred from exporting to international markets
>Not having Gold mines Germany cannot pay the reparations without exporting to acquire the Gold
>hyperinflation occurs in Germany and average Germans suffer tremendous poverty
>hatred of German enemies foments for a decade
>Hitler promises to end the subjugation, unleash German industry again and regain the land taken, he is elected
>Europe and America still suffering from the great depression while Hitler's Germany grows at double digit rates are big time mad
>Russia being friendly with Germany since WW1 (when Germany transported Lenin back to Russia to lead the revolution), together they decide to divide the Western backed Poland between them
>WW2 begins
tl;dr: German efficiency pissed off it's neighbours who then contrived an economic purgatory, leading to Hitler becoming elected and more German efficiency further pissing off their neighbours.
The European Union is basically Europe allowing German industry to dominate the entire European market following two World Wars, while the state of Germany remains a vassal and France holds the nuclear weapons.