What was the biggest disagreement between the North and the south during the civil war?

The biggest disagreement between the north and the south was slavery. The south wanted slavery but the north did not. the north beleived that slavery was cruel and wrong and in almost all northern states it was illgegal. however the south had very fertile land, perfect for planting crops like tobacco and cotton. they needed slaves to collect and clean these crops and they feared their economy would fail without the free labor from slaves. so the south decided to free it's self from the united states and become it's own country where slavery was legal. the north did not like the idea but the north did not start the war. the south attacked a northern fort and began the civil war. This all happened just after Abraham Lincoln became president. Abraham Lincoln and the north won the war and the south was re-joined with the north. Abraham Lincoln also abolished slavery in all states, both north and south.