The Fort Myers Symphonic Mastersingers will premiere an extraordinary choral work titled “The Witness: Incidents of the War of the Rebellion.” The work was conceived by the choral group’s artistic director, Matthew Koller, and inspired by the memoir of his great-great, grandfather, James Waxler, about his time serving in the Union army during the American Civil War. The memoir’s message is as cogent today as it was when he wrote it in 1888.