Military geology of Antietam battlefield, Maryland, USA—geology, terrain, and casualties

The geology of a battlefield, or that which underlies the area in which a military campaign occurs, rarely truly affects the outcome of battle. Confederate General Robert E. Lee's Maryland campaign and the Battle of Antietam fought against Union General George B. McClellan in 1862 during the American Civil War, are however, major exceptions to this rule. Lee used the geology and structure of the area in choosing the invasion route, in a major delaying tactic prior to the battle, and in the battle itself. In this article, we show the affects of geology on the battle by using standard morphometric measures to quantify terrain variables and relate these data to the numbers of killed and wounded during the battle. We also include a field guide to various locations on the battlefield where the relations between geology, terrain, and casualties can easily be seen.