The roots of military applications of geology lie deeper in France, Germany, and the United Kingdom than in the United States. Throughout history, if generally more conspicuously in the Old World than the New, military activities have locally and sometimes regionally shaped the face of the Earth by construction of major earthworks, fortresses, and excavations. Military enhancement of terrain features by walling, scarping or flooding to form obstacles which counter or deflect attack often complements the effects of natural geomorphologic agents. Topographic mapping on a national scale to depict the face of the Earth was commonly initiated under military auspices, and early government geologic mapping (e.g. in Ireland, Scotland, and England) developed largely as a military initiative. Specialist geotechnical maps were devised by both Allied and German forces during the two World Wars to guide military planning and deployment, notably with respect to groundwater abstraction, ground excavation, natural resources, trafficability, and other aspects of terrain analysis. Military operations and exercises have polluted parts of the Earth’s surface through use of explosive ordnance and by fuel leakage, and disfigured it by redundant construction works. German military geologists in particular have necessarily developed peacetime roles to protect the environment rather than the state. Yet because agricultural use and urban sprawl are restricted within the large tracts of countryside designated as military training areas, these may preserve a heritage of habitats in a fairly natural state – as valuable in terms of conservation as the many sites worldwide now preserved for their military historical record.