Answer:
a. anti slavery
b. Abraham Lincoln
c. making abolition a war goal
Step-by-step explanation:
The Union were not very successful during the first part of the Civil War and this led to a lot of discontent and lack of support for Abraham Lincoln. After the Emancipation Proclamation however, things changed as the Abolitionists and the Black Americans lent their support to him.
It also dissuaded European nations from getting involved in the conflict on the side of the Confederacy because they did not want to be seen as supporting slavery at a time when they had abolished the disgusting practice.