Ok so this dispute begins around the Nullification Crisis (see link below). Basically, the Federal Government lowered tariff taxes in the North and raised them in the South to increase northern manufacturing. Southerners did not like that. It hurt their economy. During this time period as well, the South began losing it's legislative powers in Congress due to the increasing population of the North as a result of industrialism...more people were moving to the cities for work. More people means more northern representatives, which results in more votes for northern interests. There were high taxes imposed on the South, and Southern delegates felt that they had no voting power in Washington. They felt their economic interests were being over-looked. The US had shifted it's focus from agriculture to industry. The South felt left out and felt like they no longer had a voice or say in what was going on. The Civil War occurred over economics and the Southern landholder's desire to maintain an agriculturally based society. The South's economy was almost entirely reliant on slavery. So yeah, in some sense it occurred due to slavery. Though, secession would have never occurred if the Federal government had not imposed higher tariff taxes on the southern states. No one in the south was saying "They're coming for our slaves! Them Yankee Bastards!" The Federal government wasn't coming for their slaves, but they were using a disparity among southern and northern legislators to creates tax breaks for manufacturing at the expense of the southern economy. There was a shift occurring between an agriculturally based economy and one based on manufacturing in this country, and as a result, Southern economic interests were no longer of the interest of to the Federal government. So, the South seceded.