David Decker slices a watermelon while racing by it on his horse, Gentry, to illustrate how a Federal Cavalry soldier would use a sword during the Civil War. Decker is teaching the class “From Sumter to Appomattox,” which explores the strategies and military tactics of the Civil War through a hands-on, interactive summer camp this week at the University of South Carolina Sumter. Decker wore authentic Federal Cavalry uniform for the Wednesday class.