It's true. The constitutional battle underlying the civil war was states rights vs. federal government supremacy.
Then as now, conservatives stood on the side of states rights.
First of all, your definition of a "conservative" is a load of left wing ####. Conservatives are strict Constitutionalists, and the right to life, liberty, and pursuit of happiness applies. The ability to define a human life as not worthy of Constitutional protection took legal twisting to the max... which required... attorneys... (not REPUBLICANS or CONSERVATIVES)
The Democrats of the Confederacy are a mirror of what is wrong with the US today. Confederate President Jefferson DAVIS, TN Gov ismael HARRIS.... were JDAACs (Jews disguised as Christians). The rank and file Bible Thumping non-Jewish White Christians had very little to do with slavery, as Farrakhan and others have documented. Unfortunately, those whites are really, REALLY STUPID, and basically accept whatever preacher says without questioning it, which explains why Judaism has spent so much time and money building "megachurches" and the like to control what they think (like Israel being more important than the US, and W being a "great" President - if you hate the US and cheer the US demise he presided over by being 100% anti-CONSERVATIVE).
The basic conservative private sector business friendly non-Zionist Republican (the party until 1998) was NEVER engaged in any racial discrimination.
The attempt to claim the Civil War was about "states rights" is also left wing BS. It was about the "Zionist Right" to do whatever makes Zionism richer and stronger, with total disregard for country, fellow citizens non-Zionist etc...