Here is a list of nine "top events" that led to the Civil War. While one can quibble over these, it is quite obvious that fully 7 of the 9 were direct conflicts over the slavery issue. And Lincoln's election makes 8 of 9 since it was believed that his election meant an end to slavery in the Union.
And another thing, the American Civil War (aka the war of northern aggression-LOL!) began when Confederate batteries opened fire on the Union garrison of Fort Sumter and dared President Lincoln to confront their succession plans.
The South had already seceeded from the North when Linclon was sworn in as President. President Buchanan had ordered a Peaceful transfer of all Northern bases in Confederate states to be turned over to the South. Lincoln was a politican and told people what they wanted to hear(just like obama). He offered the South a Constitutional Amendment to guarantee slavery in the South if they returned to the Union. He didn't care about the slaves ,he wanted the Southern tax money to support the Union( 75% paid by the South )linclon like obama didn't feel the U.S. Constitution was something they had to follow.