The in great need of troops, but because of segregation they missed the opportuity to get recruitments from other troops.
The major advantage is that the states have their own right to choose which laws will apply to them and in what way, based on their own interpretation of the laws.
If your talking about the time period i believe you are the answer should be Andrew Jackson.
Well, the Battle of Midway changed our entire strategy going forward, as afterward, the US was able to push in with massive victories. one reason for this, was we sunk 4 Japanese Carriers which took a very long time to make. Ultimately, it was the turning point to us winning in the Pacific massively rather than minor, or hard-fought victories.