In 1865 Congress established this cemetery as a final resting place for Union soldiers who died on area battlefields. Since that time, soldiers from the Spanish-American War, WWI and WWII as well as some family members have been buried here. The cemetery was closed for any others in 1945, More than 15,300 men are buried here. Of those, the identities of fewer than 3,000 are known. Those that are known have a rounded granite headstone to mark their grave. The graves of unknown soldiers' are marked by a small square stone bearing two numbers. The top number identifies the plot; the bottom number indicates the number of soldiers buried in the plot. The cemetery is on land known during the war as Marye's Heights.