How is the Civil War present in the story Little Women, and why does it not play a major role in her novel?
In Louisa May Alcott's Little Women, we never really see the Civil War. It hovers in the background; it affects the lives of Marmee and the girls; they each do something for the war effort. Mr. March is away at the front, and the war comes to the girls filtered through their father's almost certainly carefully worded letters home. It provides a subtext and a reason for some of the decisions the girls make, but it never seems to intrude upon their fairly sheltered lives.
It is possible that Alcott treated the war this way because her intent was not to write a war novel but a novel about a family of young women on their own without a father figure. A father away at the war can be missed and thought of fondly, but he is also the authority figure who is out of the way, and the girls are given the opportunity to spread their wings and decide things for themselves, helping them to grow up into the "women" of the title.
In fact, the closes the war gets to them is when Mr. March returns home. By then, they have grown independent and strong. This is not to say that they might not have anyway - only that they had more independence than they would have if he had been home.