The American Civil War has a MTTH of 12 months once the Upper House is at least 35% Liberal and both the John Brown’s Raid and Dred Scott Decision events have occurred.
The Dred Scott Decision event has a MTTH of 10 months but takes 20X longer pre-1845 and 10X longer pre-1855, and requires one Slave State to have at least 5 Consciousness and the Upper House to be at least 15% Liberal.
The John Brown’s Raid event has a MTTH of 10 months but takes 10X longer pre-1845 and 5X longer pre-1855, and requires one Free State to have at least 5 Consciousness and the Upper House to be at least 20% Liberal.
Consciousness is fairly easy to raise, so the key to triggering the Civil War is to increase Liberalism first to 15%, then to 20%, and finally to 35% prior to the second event firing, so that the ACW will trigger around 12 months after the second event fires.