Accurate communication was crucial to winning the Battle of Harpers Ferry, where rivers, mountains, and miles of distance separated Confederate General "Stonewall" Jackson from his mountaintop commanders. With telegraph messaging impossible and courier service difficult, signal flags became the principal form of communication. Confederate signal men occupied positions on the heights, waving flags in patterns to transmit coded messages. This laborious system took time, and Jackson complained that "the day was much advanced" before his orders were transmitted. Nonetheless, he received important intelligence from his commanders, including that "not much could be expected from their artillery so long as the enemy retained his advanced position on Bolivar Heights," and that information helped him envision the enemy and devise his plan of attack. During the Civil War, this flag system was widely used and effective despite interference from fog or mist, using one flag or torch at a time and combining three simple motions to signal a message.
