What issue constantly plagued Lincoln as the war progressed?

A. finding a way to get the Union troops to fight harder

B. finding a general who would be aggressive and win the war

C. finding a general who would not run from battle

D. finding a way to get more states to join the Union

The answer would have to be D. The only problem he was mostly worried about, was the problem of slaves. Let me explain.

The south relied mostly on agriculture, and to north, ehh not so much. The south needed slaves to run the farms, they wer lazy, and the north, well there you have a reason. The north has already outlawed slaves. The main goal for Lincols was to bring the south into the union so that they would be slave free. The south saw a perspective where once the slaves are gone, they will have to do work. Thats their issue so it was a big problem at the time.