Shades of War (Stone Soldiers #4‪)‬

Colonel Mark Kenslir has defended America from the supernatural for over fifty years. In that time, he's killed many men. Now one of those vanquished enemies has come back from the grave- and is raising a spectral army from Civil war battlefields for revenge.

Kenslir must find a way to stop an army that is already dead, before they reach Washington and plunge the country into chaos. Aided by his cryokinetic granddaughter, an amorous vampire M.D. and his stone soldiers, can the Colonel stop the forces of darkness or will Washington fall to the shades of gray?