Many people will tell you that the war was fought in order to free the slaves of the south but that would not be an accurate statement. The secession of the southern states began because Lincoln declared that no other slave states could be created but that the states that had slavery could continue to do so. Some states felt that whether a state was free or slave should be left up to the state governments. Then when Lincoln called for the different states of the Union to raise armies in order to fight the rebels of the states that had pulled out, more states left the Union. It was because these states had left the Union, and that it was seen as an open act of rebellion, that the War of Northern Aggression was started.