With a POD no earlier then 1812, have one of the major European states be a democratic federation called die Vereinigte Europäische Provinzen (meaning United European Provinces). The state must have German as it's lingua franca, and must include non-Germanophone territories, as well as all of OTL Germany's territory (Elsass not necessarily, but if you can do it, even better).
The mightier and more influential the VEP is, the better.
The VEP must be a stable democracy!