“The Union in defending itself also advanced the cause of emancipation, abolition and full citizenship for African-Americans.”
That is an interesting comment.
Tell me more about how the slave state of Maryland attacked the slave state of Virginia.
And how the slave state of Delaware attacked the slave state of North Carolina.
And how the slave state of Kentucky attacked the slave state of Tennessee.
And how the slave state of Missouri attacked the slave state of Arkansas.
And how the slave state of West Virginia . . .
Were the slave states attacking the other slave states to protect slavery?
Or were the slave states attacking other slave states to stop the other slave states from stopping them from freeing their slaves?
Such arguments are pure nonsense, merely a distraction from the totally valid point that emancipation & abolition became increasingly important to the Union cause, as illustrated in Julia Ward Howe's Battle Hymn of the Republic.