The Romans defeat the German tribes one by one, and extend Roman rule to the banks of the Elbe or maybe even the Vistula. How does this effect subsequent European history up to now?
There are so many possibilities. The first to come to mind is the avoidance of the Hunnic and Gothic invasions of Rome. Rome withstands the Huns but fragments politically and the emergence of separate European states occurs at least two centuries earlier.
I was thinking also along the lines of no Germany/France conflict, which would have had a pretty major effect on European history.
