Question: Is there any factual basis for the story of the little girl General Jackson befriended? I can't find anything about her, or anything saying she is fictional.
Question: It takes more than skilled generals and troops to win - without food, and supplies, skill is just an empty threat. Why didn't the south realise this during the time the movie takes place?
Answer: Pride, honor, and respect were some of the characteristics of a Southerner's perspective during the Civil War, and did not change through the war. At this point of the war, however, the Confederates knew they were now on the defensive, no longer fighting for either slavery or states' rights, but the survival of their land, farms, and homes against foreign invaders (Union troops) who were using "scorched earth" tactics to break the South's will and ability to fight. That alone, kept them fighting even though victory was not going to happen for them.
What are scorched earth tactics?
Destruction of farms, crops, livestock. Also destroy every town that the Union troops arrive at.
Question: Where was the civil war battle fought nearest Madison, Wisconsin?
Answer: The nearest one I can find listed was at Kirksville in northern Missouri.
Answer: Yes, she did exist. Through books.google.com, I found a book "Cemeteries of Caroline County, Virginia: Private Cemeteries" by Herbert Ridgeway Collins, that confirms Jane did live, that she and Jackson were close, and that he arranged for her burial after her death.