The War to Prevent Southern Independence is the more proper title for the Civil War. The South did not want to take over DC or the North. There exists a vitriolic Lincoln Cult who cannot countenance that Lincoln might have been motivated by money and power in engaging in the Tariff dispute which began in 1824. The Tariffs amounted to a triple tax on Southerners. All the benefits went to Northern manufacturers. By the1880s the average tariff was in the 45% range. Ninety percent of all Federal revenue was financed by the tariff. Lincoln said he would invade the South if they did not pay the tax. The naval blockade of the Southern port was because of the tariff. The tariff was an important cause of the war.
No serious historian would say that the Southern states were invaded for the purpose of freeing slaves; the war was about destroying any secession movement.
Lecture 1 of 10 from the Steven Berger Seminar: Thomas DiLorenzo on Liberty and American Civilization.