During the American Civil War, both the Union and Confederate sides relied on spies to gather crucial information about enemy movements and strategies. These spies used various methods, including disguises, coded messages, and secret meetings, to relay information without being detected. Notable figures, such as Harriet Tubman and Belle Boyd, played significant roles in espionage efforts. Their intelligence helped shape military decisions and outcomes, highlighting the importance of covert operations in warfare. Spies often faced great risks, as capture could lead to severe consequences, including imprisonment or execution.