The election of Abraham Lincoln did cause the outbreak of the Civil War, but only in the immediate sense.  To think of what this means, think of a person who smokes, is terribly obese, and never exercises.  The person goes out for a walk and has a heart attack.  Did the walk cause the heart attack?  In a sense, it did, but the heart attack was really caused by all of the things that had gone before.  Lincoln’s election was the same way.

Lincoln’s election was the relatively immediate cause of the Civil War.  Lincoln had been elected without getting any votes in the South.  The South felt sure that he would rule only for the benefit of the North.  They were sure he would try to abolish slavery.  They felt his election was a threat to them and so they seceded.  Lincoln’s actions with regard to Fort Sumter then started the war just over one month after Lincoln became president.

But Lincoln’s election was only the last straw.  The true cause of the Civil War had been building for decades.  The Civil War was caused by the fact that the South had slaves and the North did not.  This caused the two sections of the country to believe that they had different needs and different interests.  As far back as 1820, they were already in conflict with one another over political issues.  This conflict really heated up after the Mexican-American War.  All of these conflicts were what really made the two sides distrust each other.  Therefore, they were the true cause of the war.