There were many issues that created the war that turned brother against brother. Out of the several different issues, the greatest one was slavery. Thus, slavery was the major factor that caused the American Civil War.
Firstly, the plantation system made way for the mass production of crops. This in turn, made the need for additional workers. The plantation owners required additional slaves to support the demand for workers. The abolitionists didn't want to go to war over slavery, and since slavery was helping the United States become a global leader they didn't mind as long as the South followed the general restrictions to keep slavery in the South and away from them.
Until, it went too far. The South kept pushing slavery further and further, bending the rules such as: the 36'30 line, the Missouri Compromise, and the Compromise of 1850. Each of these events kept separating the United States further apart and pushed more and more for war.
At about the same time, Kansas and multiple slave rebellions created more tension between the North and the South. In 1831, Nat Turner organized a slave revolt in Virginia; this made the South fear that more revolts may occur. The North also did not like the fact that the South could not control their slaves that well. The Kansas-Nebraska Act left it up to the territories to decide whether to become a free state or a slave state. This made many abolitionists as well as pro slavery supporters move to Kansas. Emotions between the two ran high and violence erupted. Hundreds of people on both sides died before peace became restored. John Brown's attack was one of the final steps that sparked the war. He and eighteen followers raided a United States Arsenal in Harper's Ferry. Brown hoped to create...