The rupture between North and South was caused by an inherent conflict between their economic systems. The industrializing North poured its money into manufacturing and internal improvements such as railroads and canals, while the agrarian South still invested primarily in land and slaves. The contrasting laws and cultures needed to sustain each region's growth made divisions between the two groups extremely difficult to reconcile.
The main priority of most Northerners was not abolishing slavery, but thwarting Southern attempts to secede from the United States. Supporters of this theory claim that the North believed no state had the right to secede from the nation, and would have accepted the continuation of slavery in some form had the South agreed to work within the existing governmental system.
The North and the South fought the Civil War primarily over the institution of slavery, and whether it should continue to exist in the United States. From this perspective, Northerners are perceived as abolitionists or at least opposed to the power of slaveholders. Southerners fought primarily to protect their property rights (i.e. the right to own slaves).
Southerners went to war primarily to protect the broader right of state governments to remain the primary authority for passing and enforcing laws within their borders. The right to own slaves was secondary for Southerners to the right to protect their interests against those of the federal government.
When examining the evidence in this exercise, rank it on a sliding scale of overall relevancy from "Very Relevant" to "Not at All Relevant." Relevant means that the evidence is not ambiguously related to the argument; it clearly strengthens the case for a particular thesis. For example, a piece of political satire may carry less weight as evidence then a speech made by a prominent political figure. By choosing "Not at All Relevant" you are saying that the evidence does not support the specific thesis.