Actually, the DEMOCRATS went to war to EXPAND slavery.
The REPUBLICANS were formed to prevent the EXPANSION of slavery.
There were plenty of pro-Slavery democrats in the North.
Just as there were many anti-Slavery Republicans in the south.
Virginia for example. When Virginia seceded.
The anti-slavery Virginians in the west seceded from Virginia.
West Virginia is the only State formed by secession.
Expand it to where?