BATTLES NOT FOUGHT--MAPPING GEOLOGY AND TERRAIN AS DEFENSE IN CIVIL WAR KENTUCKY

Terrain was a key consideration in tactical and strategic planning during the American Civil War (1861– 1865). The Kentucky Geological Survey has collaborated with experienced living-history specialists and amateur historians to develop lidar-based maps showing the role of geologically influenced terrain in defensive positions that played key roles in Kentucky Civil War campaigns.

Steep terrain was prohibitive for large-scale infantry maneuver. Unfortunately, contemporary field manuals do not explicitly quantify slope factors as a consideration for infantry maneuver. The authors used authentic Civil War infantry footwear to walk across ground with varying slope angles to estimate approximate limits on infantry maneuverability. These limits were then extrapolated across the landscape using a slope map derived from available lidar. Infantry weapons could fire roughly 400 yards and were generally lethal at a range of 100 yards. Civil War artillery operated by line of sight, and each model of cannon had specific ranges of effectiveness. Historical records document the locations of these batteries and the cannons reported to have been positioned in them. A lidar-based visibility analysis can be performed to estimate the effective ranges of infantry and artillery and to quantify the overlapping fields of fire in each domain. When combined, these geospatial products can visually demonstrate the barriers and lethal fields of fire which defended key positions.

Quantified defensive maps of the Camp Nelson supply and training depot for the Union Army, and for fortifications around Cumberland Gap, clearly illustrate the impregnable nature of each site. At Camp Nelson, Pleistocene river entrenchment into a carbonate plateau developed steep palisades to defend the depot location. At Cumberland Gap, topographic relief related to a thrust-sheet structural ramp provided prohibitive terrain for approach maneuver and long fields of view for artillery. Despite both being key strategic targets, neither was directly attacked by opposing forces during the war.