AHC: united Germany, divided but unifying France

The challenge is to come up with a scenario where you have a France which was divided into dozens of petty states until at the earliest the late 19th century, while there is a Germany that has a history of unity since at least the 15th Century. How does this happen? Do we have to go all the way back and say that William of Normandy is killed at Hastings, butterflying Plantagenet adventures in France? Maybe a German royal house takes England instead, and fight to add "Germany" to its holdings?
 
Having the Hohenstaufens last longer is a good start, but your best bet is to prevent OTL Philip II Augustus from lasting long. His 43-year reign set France up from "weaker than its nominal vassal the Angevins" to solid medieval kingdom.
 
Top