Antietam, Maryland. Captain J.M. Knap's Penn. Independent Battery E Light Artillery (U.S. Civil War) This product title refers to a historical artifact related to the U.S. Civil War, specifically Captain John M. Knap's Pennsylvania Independent Battery E of Light Artillery that participated in the Battle of Antietam, fought on September 17, 1862, in Maryland. The battery was part of the Union Army during this significant battle of the Civil War, which is considered one of the bloodiest single-day battles in U.S. history. The product's exact nature (e.g., a photograph, artwork, artifact, or replica) isn't specified but suggests it may be related to the battery or the battle itself.