I am ridiculously fucked. Empress got 1-turned out of the fog, and I have no idea how. In order to try to figure it out, I loaded up the previous turn's save and sent my Great Spy to find the stack:
Here's where it was. I do not understand how it got from there to be able to attack the Empress in a single turn. I know Sian has Engineering and Construction; that lets him cross rivers with roads and makes his roads 3-to-1 instead of 2-to-1. But I have cultural control of my first ring, so once he declares, my roads cost a move as normal. So I don't have any idea how he gets his units to "just outside my city" and
still has move left to attack with. If someone could explain this, I would appreciate it. The kicker is, since I didn't see his stack appear in my view (and I have sufficient cultural control that I had vision 2t in on most of our border), I held my own stack a little ways back so that I could defend if he went for my northern cities.
Repositioned to defend Wheel of Fortune, which I don't think he can reach, but clearly
something is wrong with my understanding of game mechanics.
Here you see the counterattack I can muster this turn. I've sent a musket to his northernmost city to harass and cut off his luxuries, and next turn I can boat Descartes with a cuir/musket combo (I'm going to raze the city, obviously).
More troops are coming out, but I don't know if it will be enough. Sian is experienced in MP and I am not. Now I guess we find out if greenline pounces on Sian's backline before Jowy does so on mine.