I am playing as the French in the Grand Campain. Both Prussia and Saxony declared war on Bavaria. As a good Ally, I push the Saxon and Prussian troops out of Bavaria and into Saxony. I destroy the Saxony Army, Capture their cities, build supply depot train through the Saxony territory and invade Prussia. The turn I move into Prussia, Saxony changes sides. Even though I won all the battlies that turn I end up losing Victory Points. I lose National Morale. I lose the 4 Saxony cites that were producing for me and I lose my train of supply depots running through Saxony territory into Prussia which are not even in Saxony Cities.
Somebody show me a single benefit to the Frency for Saxony changing sides. One benefit. How do you guard against the destruction of you supply lines by an event you have no control over.
Even the Game Engine knows it was a stupid. That is why I ended up with less victory points and National Morale after the event than before the event. If the Game Engine penalizes the player for the event, maybe, just maybe that is a sign the event is not designed correctly. This is worse than the "Accept a Surrender" penalty.
Now I have a French Army in Prussia with no supply. By Switching sides, Saxony has forced France to do something that Prussia could never have done, leave Prussia.
What are my options now. Retreat across Saxon and rebuld my supply lines.
Or why don't I declare war on Saxony and capture the supply lines I have already built?