This month they posted on facebook that they had nothing to announce, but they had a network committed but are currently hammering out negotiations with all the major players.
"Network announcements are the network's prerogative, so unfortunately that's not something we will discuss. And yes, our cast is absolutely on board. The thing to remember about the cast is that many of them approached us about participating. Usually it's the other way around. We are very fortunate to have a cast that's energized and anticipating working on this. If changes have to be made to accommodate schedules, we will announce that here."
Preproduction is planned for December, shooting in March. Also, the title had been changed to Grant vs. Lee because in testing it with average Americans it was found to be about 1000% more effective. It doesn't actually describe the real series, as it will cover much more of the war than just Grant vs. Lee.