A View from the Saddle: Using Google Earth ® to Interpret Napoleonic Sites

Edna L. Mueller, M. Sc., Senior Geophysicist,

Paterson, Grant & Watson Limited, Toronto, Canada


Satellite imagery and high resolution elevation data and the software used to view and manipulate them have long been in the realm of geographers, geologists and engineers. Recently, this data has become available and accessible to the average home computer user. Google Earth ® is the best known example of a web-based program that combines satellite imagery, elevation and geographic information (roads, sites of interest, etc.) In addition, there are many federal web sites, known as geoportals, which contain more information about a specific country.


A satellite image is a flat “photo” of the earth’s surface. For the purposes of this paper and presentation, 90m resolution elevation data is merged with satellite imagery to render a 3-D view that can be viewed from any position and angle. Looking at a scene of a battlefield in 3-D can provide the viewer with information about the terrain such as line of sight, slopes of hills and its effects on troop mobility and strategy.


Typical battlefield manoeuvre maps try to condense the movement of military units in space as well as time. A simple overlay of such maps onto a 3-D elevation surface can aid in the interpretation of a battle scenario. Further, the individual military units can be modelled and animated independently. Now, the battlefield scenario becomes 4-D, moving in 3-D space and time.


The Battle of Rivoli (14-15 January, 1797) of the northern Italian campaign was chosen to animate and analyse due to its dramatic topography and its smaller and less complicated battlefield scenario.


Another use of these geoportals is to travel in time. For example, France’s geoportal at the Institut Geographique National (IGN) combines satellite imagery, present day cartographic maps, and the historical Cassini maps of France published from 1798 through 1812. Dissolving from one map to the other shows how cities have grown, rivers have changed their course, and how the countryside was perceived at that time.


“Sight-seeing” is the simplest and often the most satisfying use of Google Earth ®. These aerial views can show areas of interest, Napoleonic or otherwise, that may be completely obscure from the ground.


Finally, Google Earth ® and other geoportals can transport you to locations that are either too remote or too costly in time and money to travel to in person. The presentation ends with one such example, a visit to Longwood House, St. Helena.