Tillie Pierce's (also known as Matilda Alleman) "At Gettysburg" is an intriguing book that follows the life of 15-year-old Tillie as she witnesses and experiences the Battle of Gettysburg. During the first day's fighting, Tillie's family moved her out of town to a farm, thinking she would be safer there. As it turned out, Tillie ended up right behind the Union lines on the second and third day.
The farm where Tillie stayed became a field hospital, where the young girl witnessed much suffering and death. The book Tillie's own account of her memories and experiences from the battle. Though written years later, it is considered to be a very accurate and firsthand source, not to mention a remarkable journey behind the front lines at the Battle of Gettysburg.