Eh, the US went to a civil war because half of the country (the south) started attacking national (i.e. union) armories/forts.

Of course there was some lead up to that but the actual flashpoint is that the south started it and they didn't do so to free northern slaves. Northern congressmen were not pushing for any bills that removed slavery from the south and etc; there wasn't an imminent (i.e. during Lincoln's presidency) existential threat that the North would end slavery in the South except the one the South manufactured.