Touch of Magic

I assume your research has revealed that post-Charlemagne the Franks split up--into 3 parts. Their language was Germanic, but the West Franks adapted the Gaulic Latin which evolved into French. The East Franks kept the Germanic (they call Charlemagne "Karl der Grosse"). The French name for Germany, "Allemagne" comes from the Roman name for a confederation of German tribes--Allemanni--which became a duchy after it was conquered by the Franks. Anyway, the upshot is that only one language is descended from both the French and the Germanic (though not the Frankish Germanic). We call it "English".