Civil War help?

Question

How was the Civil War a final triumph of the idea of a federal union over the power of the individual states?

Answer 1

States rights, as advocated by the Southern states, and Federalism, as advocated by the Northern states, was THE dividing issue prior to the Civil War.
The South used states rights to extend slavery into the new Western territories. And the Dred Scott decision gave an enormous power to the South to extend slavery--and even threatened to reintroduce slavery into those states where it was prohibited, such as Illinois.
The North had a larger population than the South. If it were up to a majority of people--without the check of states rights--slavery could have been if not eliminated, at least restricted, throughout the whole country.
The Constituion that the Confederacy established was almost identical to the US Constitution, although one of the areas where it differed was in its establishing states rights in the Confederate States.
When the North won the war, it was the federal government that now determined that slavery was prohibited everywhere. And it was the federal government which imposed reconstruction on the South.
According the Shelby Foote, the historian, it wasn't until after the Civil War that the United States was spoken of as a singular noun--one no longer said "The United States ARE..." but instead "The United States IS...."

Answer 2

The states that succeeded didn't win. The states that stayed in the union, won the war. And the Southern states were more independent in their organization than the North, which contributed slightly to their defeat.