Geology has controlled the outcome of battle since warfare began. Understanding the nature of ground, the opportunity for active defence and tunnelling, the ability to move freely across tracts of terrain, and the provision of natural resources are some of the problems that have faced armies for centuries. Peter Doyle specialises in the interpretation of historic terrain, and is a noted expert in the field having studied battles both in the USA (Revolutionary War, Apache Wars, Civil War) and Europe (Gallipoli, the Western Front, Normandy, Arnhem, Battle of the Bulge). His conference, Terrain in Military History, held at the University of Greenwich in 2000, formed part of the development of International Conferences in Military Geosciences. In 2007 and 2014 he was invited to lecture on the topic to the Cadets and Faculty of the US Military Academy in West Point, New York, USA.