The Greenhow Cipher — Uncover the Confederate Spy Ring

Charleston in 1861 becomes the nerve center of Confederate espionage when Rose O'Neal Greenhow establishes her network from Washington. The Heyward-Washington House, built in 1772 by Daniel Heyward for his son Thomas Heyward Jr., signatory of the Declaration of Independence, had hosted George Washington in May 1791. This 2-story Georgian house, classified as National Historic Landmark in 1973, conceals in its period gardens the first dead drops of the Southern network. Its outbuildings restored according to 18th-century methods camouflage the codes that Greenhow transmits to her agents infiltrated in the federal capital.

Charleston Library Society, founded in 1748 by 17 members as the oldest subscription library in the United States, becomes the intellectual center of resistance. Its 1914 building at 164 King Street, near Washington Square, houses 150,000 volumes including Southern spy correspondence you must decrypt. The first reading room opened to the public in 1792 serves as cover for secret meetings of Confederate sympathizers. Its Civil War archives contain the real code names used by the Greenhow network to coordinate insurrection from Charleston.

St. Michael's Church, Anglican church completed in 1761 with its 195-foot steeple visible for 20 km, functions as a watchtower for spies. Its carillon of 8 bells imported from England in 1764, first in the American colonies, transmits coded signals to Confederate ships cruising offshore. Located at 71 Broad Street, survivor of the 1838 fire and 1885 cyclone, it conceals in its adjacent cemetery the tombs of notable Confederates where secret messages from the Southern spy network you're tracking are exchanged.

The Old Exchange and Provost Dungeon, built in 1771-1772 as commercial building then used as British prison during Revolution, returns to service for federal prisoners. George Washington gave a speech there in 1791, but in 1862 its underground cells imprison double agents discovered by your investigation. Classified National Historic Landmark in 1960, this site at 122 East Bay Street 0.5 km from Washington Square reveals in its dungeons the interrogations of federal spies infiltrated in the Greenhow network.

Your mission ends at Charleston City Market, opened in 1807 across 4 blocks of pink brick buildings along Meeting Street. This Confederate economic center during the Civil War (1861-1865), classified National Historic Landmark in 1973, hides under its ballast stone pavements from 18th-century ships the last secrets of the spy network. You take away intimate understanding of Charleston as laboratory of Southern secret war, where every Georgian facade and magnolia garden concealed invisible threads of a web extending to Washington salons.