Most battlefields have more open space than woods. Some have their share of woods. But Shiloh (American Civil War 1862) was fought over an area chiefly of woods and swamp with a few fields or clearings sprinkled about. While game map creation is always a time-consuming task, the Shiloh map is even more problematic as the important clearings in every case do not perfectly transform to a hex-based map at the scale being used ( 1 hex = about 250 yards).
As gamers understand, a heavily wooded battlefield slows troop movement and makes unit cohesion more difficult. Woods also offer defenders (in this case primarily the Union side) the advantage of cover. Shiloh offers plenty of opportunity for these game issues to be represented.
The game map for Shiloh is based on the 1993 Shiloh Battlefield map by the McElfresh Map Company, which used two primary sources: the Atwell Thompson map completed in 1900 and the Edwin C. Bearss historical base map prepared in 1972 for the National Park Service.