During my writing I look at a lot of maps!
Many maps survive from this American Revolution era. Maps of cities, maps of the colonies and the surrounding territory but also maps detailing battles. It is helpful to see how the people at the time marked, tracked and saw their own battles. We make modern maps of such events but it is always going to be clouded, in some manner, by either our own bias or the bias of conflicting sources or the change of terrain in 200 years.
No one alive today actually lived these battles, we can only read about them in the letters and information left behind.
Primary source maps can be useful in a variety of ways. They may not show you all the movements of a battle - which side appeared when or timeline - but they can give you a view into the minds of the period. What did map makers during war find important? What was the style of showing different aspects of a city, of land, of enemy combatants?
You can see, in this first map, siege lines are noted in red outside of the city as well as ships in the harbor. A lot of detail is given to the land and water around Charles Town itself so you can almost miss these aspects of war within the map.
From this expanded view it can be difficult to see some of the details of the siege. However, when you look in closer, considerably more detail appears!
Below I have a close up of the city of Charles Town itself within this map.
Now we can see the detail of the city streets, the boom chain across the Cooper River, the names of docks and even of ships. The red lines of British siege and Continental headquarters are all apparent. We have street names, thicker lines to show where the defensive walls were in place. The portions in red pop out as clearly noting 'battle' aspects new to the city and terrain.
This detail is invaluable for a writer. I can use this map to make a reader feel that intimacy of the specific name of a dock or where the headquarters lay in relation to the first parallel. It is small details that make a scene more real. Maps, such as this one, give me that window into a world I cannot experience in person because it is part of the past. Maps like this one can give a story more life.