What changes would be needed for the the Hundred Years' War to be fought between England and the HRE, instead of England and France?
Could English kings fight a a hundred year long intermittent war over their claims to the Holy Roman Empire, instead of to the Kingdom of France?
For a full swap, could the latter stage of the Guelphs and Ghibellines conflict be preempted or redirected, so that it's French kings instead of German kings trying to take over Italy?