A map that shows slavery was the cause of the Civil War

I like maps. They provide the most compact form of information display known to man. And if you click here, you will see the map that displayed the percentage of slaves in each county in America in 1861.

Abraham Lincoln was obsessed with this map and with the progress of the war as it freed those slaves. The map itself makes it clear that slavery was at the base of "The Rebellion," and Lincolns obsession with this map makes it clear how important the Civil War and its effect to free slaves was to him.