 During the American Civil War (1861–1865), because of this railroad network, Petersburg was key to Union plans to capture the Confederate States national capital established early in the war at Richmond.Nine months of trench warfare were conducted by Union forces during the 1864–65 Siege of Petersburg.Battlefield sites are located throughout the city and surrounding areas, partly preserved as Petersburg National Battlefield by the National Park Service of the U.S. Department of the Interior.