I'm pretty sure his biggest objective in the civil war was to (B.) which is Save the Union.
The correct answer to this open question is the following.
Unfortunately, you do not specify a specific topic to develop the argument. An argument about what?
What is your compelling question? We cannot cite evidence of your research because you did not mention what is the topic of your research.
If we can help with something, we are going to set our own example based on our own topic.
How about the following.
Compelling question:
Was the Revolutionary War the last option for Patriots to get Independence from Great Britain?
Argument/Evidence:
1.- Yes, it was the only option after the number of aggressions and aggravations from the British crown. The English government never had the "openness" to negotiate another valid solution.
2.- Colonists were sick and tired of the heavy taxation imposed by the English government. We are talking about injust taxation such as the Navigation Acts, the Stamp Act, the Townshend Act, or the Tea Act.
3.- The worst part of it was that colonists had to pay those taxations but they did not have a voice in the British Parliament.
Some of the peoples it conquered didn't want to be ruled by the Incas and were rebellious, mainly, and it was so big that it couldn't keep the conquered in line very well.
Answer:
The rights of citizens would be better protected by having both federal and state levels of government.
Hope this helps!