Answer:
A Southern victory at the Battle of Gettysburg would turn the tide of the war to the South's favor.
Explanation:
The reason for this answer I believe is that the Battle of Gettysburg was a major and decisive victory for the Union, and one that, overall, led to the surrender of the Confederate forces. Perhaps if the North had lost the battle, the death toll and moral toll on the Union forces, and civilians as well, would have forced Lincoln to cut the war short and provide a peace deal to the Confederate States. If after a loss at the Battle of Gettysburg wasn't enough to coerce a surrender out of Lincoln, the momentum that Lee and his army would have gained from such a decisive battle so close to the Capitol would almost certainly catapult them to a quick victory if they managed to keep pushing to the White House.
Hope this helps,
Sam
