To many people, especially in the north, they would be fighting the war
1. keep the union intact
2. promote the fugtive slave law
3. stop immigration
4. prove they were right

The answer is 1. keep the Union intact
The main point of the civil war was the north wanting a strong central gov. to be in control where as the south wanted each individual state to have its own gov. so they could be in control of themselves.