Her books have been popular with students and teachers.
Jean Guenter of the Shepherd College bookstore said the visit by Ernst is part of an effort she has started to bring authors of children's books to the area to speak.
Guenter believes hearing such authors will help students better connect to subjects like history and the Civil War.
"Now maybe the kids will have a spark of interest," Guenter said.
Ernst said although she lives in Wisconsin, she has fond memories of her times in Maryland, and in particular the summers she spent in Western Maryland.
After reading to students, Ernst fielded questions from youngsters who came from Shepherdstown Elementary and St. Joseph Catholic School in Martinsburg.
Her stories tell about tough situations children faced during the Civil War.
In "Retreat from Gettysburg," the story focuses on a young boy named Chigger O'Malley, who lived in Williamsport when the Confederates were passing south through town during their retreat from the Battle of Gettysburg.
In the book, Confederate soldiers take over O'Malley's house, and they order the boy to take care of wounded Confederate soldiers in the house.
O'Malley is torn over whether to obey the orders because his father and three brothers - all members of the Union army - were killed in the war.