The Holy Roman Empire was centered in modern day Germany and did not hold any lands in Spain and France afaik (except maybe some on the easter border of France).
In the time frame you are thinking of however both the HRE and Spain were ruled by the Habsburg family which led to wars with the French King.
http://en.wikipedia.org/wiki/Habsbur...nish_Habsburgs
This might be splitting hairs, but I think it's very interesting. It were often not the countries/empires fighting to expand their lands but the families trying to get more power.
Might well translate into Ulmish vampire bloodlines fighting for control behind the curtains.