This one would be set in about 1864, and follow the events in the harry turtledove book guns of the south, if your familiar with it.
I would either be second in command of America will break, or, and this is my preferred one, second in command of a rival group helping the union army. I would be with a small group of soldiers whos camp is attacked by a fast moving band of confederate army cavalry and raiders, there to hit it and specifically capture me.
I would be taken prisoner, talked into surrendering, but be unhappy about it, naturally.
If this appeals to anyone, do tell.
It helps to be familiar with the book, but if your not, i can talk you through it.