If her mother was aboard this ship, perhaps she visited Louisiana during the war. It sounds as if every Confederate in western Louisiana attacked this ship.
This uniform was presented to James V. "Jimmie" Johnston by the crew of the U.S. gunboat Forest Rose, for gallantry in action during the Civil War. He had accompanied his mother to visit his father, Captain John V. Johnston, aboard the gunboat in peaceful waters on the Mississippi. As the vessel approached Waterproof, Louisiana, in February 1864 it came under attack by a Confederate force. When the gunboat's regular powder monkey, who carried powder to the gunners, was killed early in the battle, young Jimmie took his place until the Confederates were repelled. The crew presented this uniform to the six-and-a-half-year-old boy they called "Admiral Johnston" for his bravery. Johnston proudly wore the outfit—with a stag-horn knife tucked into his waist—for a photograph.