[Michael81Dus]

Charlemagne wasn´t French. At that time, there was no French or German nationality - his three sons divided the empire and therefore founded the (rough) nations of Franche, Benelux and Germany.

[NovemberCharlie]

If you want to get technical about it, there was no Germany in 1800, just Prussia and the Holy Roman Empire. And Charlemagne was certainly a Frank.