With a POD after 1250, make it so that there is no one German nation. There may be a large region of what is OTL Germany (defined by its current borders) controlled by a given kingdom, but it must be divided into at least two kingdoms.
A continued HRE does not count as "no Germany". Whether disunited or not, it still is nominally one state in control of the area in question.
Large areas being controlled by France or another power is an acceptable method of meeting this challenge.
Bonus points if you can do this after 1848.