Civil War PBL Project

The high school is going through the first week of the PBL cycle. Right now we are choosing our essential question for our Civil War project. The high school girls are thinking about doing the project together. We might do the project in separate groups and then come together or we might just do one big project together.The question I am thinking about exploring is:

" How did Abraham Lincoln's decision to change his view on slavery affect the outcome of the civil war?"