One interesting fact which I am sure most people would never guess is that casualties were just about identical for both armies.
In fact the best sources show the Confederacy lost just a tad less than the Union.
Lincoln knew that given enough battles with equal or even higher Union losses the Union would still win the war. He called this: "the terrible arithmetic". The Confederate white population was less than 6 million. There were 22 million in the North. There was never really any doubt which side would win the war if the Union remained determined to keep fighting.