Colonial Jewelers 11th Anniversary charm: Monocacy Battle. Monocacy National Battlefield is a unit of the National Park Service, the site of the Battle of Monocacy in the American Civil War fought on July 9, 1864. The battlefield straddles the Monocacy River southeast of the city of Frederick, Maryland. This charm can be worn on a charm bracelet or as a pendant. 14k yellow gold or sterling silver.