Considering the fact that the French were the Germans' biggest continental rival did any emperor ever ally with the English to try and crush them?
While much more can always be said on the topic, I summarized a bit on the relationship between Charles IV of Bohemia/ HRE and Valois France before in: The info box for the Wikipedia page on the Hundred Years' War shows the Kingdom of Bohemia, a Holy Roman Empire vassal, as an ally of the Valois. However, the article shows no evidence or sources. Is the infobox wrong?.