Answer:
The Union had to invade, conquer, and occupy the South. It had to destroy the South's capacity and will to resist — a formidable challenge in any war. Southerners enjoyed the initial advantage of morale: The South was fighting to maintain its way of life, whereas the North was fighting to maintain a union.
Explanation:
The extension of slavery into the western territories.
For a specific instance, see the landmark supreme court case Dred Scott v. Sandford.
Charleston was an incredibly important city in the South because of its location--it was located on a prime piece of coast line that made importing and exporting goods relatively fast and easy.
