1980s, a computer error (some states that it couldn´t have been a mistake and that it was Reagan himself that did it, before being eliminated by a general´s plot) cause the launch of ICBMs from an isolated base.
The Red Army pushes into western europe, while that happen, the Polish armies leads the siege of west Berlin, eventually crush all resistance with an iron fist.
France leaves NATO in panic, makes a separate peace with the Warsawa Pact.
A few years later, a pro-us military faction launch a coup in France, France is wracked with social tensions following WW3 and a civil war starts, NATO and Warsawa pact forces soon intervenes. Polish forces smashes several US divisions and put the White and Red on the Eiffel Tower.