{"nrhp_refnum":"89001062","name":"Signal Hill","other_names":["Wilcoxen Signal Station","44pw138"],"category":"site","location":{"address":"Signal Hill Rd. and Blooms Rd.","address_restricted":false,"city":"Manassas","county":"Prince William County","state":"VA","lat":38.751639399000055,"lon":-77.43832640399995,"geom_source":"nps_gis"},"listed_date":"1989-08-08","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Military","Communications"],"significance_levels":["national"],"summary":{"what_it_is":"Signal Hill, also called the Wilcoxen Signal Station, is a Civil War earthen fortification and signaling station on the highest ridge near Manassas, Prince William County, Virginia, about a mile east of the old Manassas Junction.","why_significant":"It served as headquarters for a network of Confederate signal stations during the First Battle of Manassas, where Captain Edwin Porter Alexander used semaphore (wigwag) signaling in warfare for the first time. His warning of the Union flanking column at Sudley Springs was credited with affecting the battle's outcome. The earthworks remain largely undisturbed.","narrative":"Signal Hill is a wooded ridge near Manassas, Virginia, topped by the earthen remains of a Civil War fortification and signal station. The works cover a site about 1,200 feet long, with embrasured artillery emplacements, parapets and a surrounding trench; six of seven bastions survive. Its importance lies in communication rather than combat. Before the First Battle of Manassas, Confederate Captain Edwin Porter Alexander made the hill the central station for a chain of signal posts along the Bull Run line, using semaphore or wigwag signals. On the morning of the battle he spotted a Union column crossing Bull Run toward the Confederate left and sent warnings that allowed troops to be shifted in time. This was the first use of the semaphore system in warfare. Union forces used the hill afterward. Later owners protected the earthworks, and the city of Manassas began acquiring the land for a park in 1972. Two houses have damaged parts of the fort, but most of it remains intact.","period_of_significance":"1861-1865","architect_builder":null,"architectural_style":null,"criteria":["A"],"status_note":"Wooded hilltop with six of seven original bastions surviving; one house has destroyed the southwest bastion and another has cut into the fort, and the trenches have seen metal detecting. Partly acquired by the city for a park starting in 1972.","vacant_flag":null,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:52:00.633093-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/93/6788/41678893/content/electronic-records/rg-079/NPS_VA/89001062.pdf"},"photo":null,"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/41678893","wikipedia":null,"wikidata":null},"indexable":true,"url":"https://nationalhistoricalregister.com/virginia/prince-william-county/signal-hill-89001062/"}