Civil War battles are commemorated in Fredericksburg and Spotsylvania National Military Park. Formed by an act of Congress in 1927, the national military park preserves portions of the battlefields of Fredericksburg, Chancellorsville, the Wilderness, and Spotsylvania Court House. The Fredericksburg National Cemetery, also part of the park, was developed by the federal government after the war on Marye's Heights on the Fredericksburg battlefield. It contains more than 15,000 Union burials from the area's battlefields. Many unidentified soldiers were buried in mass graves.