The Secret of Richmond Manor, Bonnets and Bugles Series by GIlbert Morris and published by Moody Publishers.
Fourteen-year old Leah Carter lives with her uncle in Virginia, tending to his illness and awaiting the end of the Civil War. As the hospitals fill, Uncle Silas volunteers the use of his home as a temporary medical center, and the two of them move to a house he owns in the country. But, the house isn't empty! Somebody is stealing food and making strange noises in the night. Supersitious townsfolk believe it to be haunted, but Leah finds something even more frightening!