Continuing the discussion of mapmaking during the American Civil War, we must ask the question: how were the maps made? Last week we highlighted the need for maps, but how did the cartographers actually solve the problem and create the needed charts?

Let’s take look at some history and a little science…

Use Your Eyes

Ideally, a cartographer saw the land he was mapping. Carrying a notebook and either walking or riding, he made estimates, noted the topography, and started sketching. Skillful mapmakers often had backgrounds in engineering or other sciences and had been trained to notice elevations, directions, and how to use the tools of the trade.

The most accurate maps had distances surveyed and measured by chains. However, Civil  War cartographers did not always have the luxury of a team or the time to make sure precise measurements. They had to learn to estimate and make observations based on what they saw. Sometimes, mapmakers got their information from scouts who would report the location of a ford, the slope of a mountain, or the distance to a town.

Whether they relied on others’ information or collected their own, perspective and what they saw with their own eyes formed the groundwork of mapping.

Use The Science

I could sketch a map of the library where I’m sitting right now. You’d see the building and the rooms, but with a quick sketch based on what I see, it wouldn’t be accurately to scale.

Now amplify that situation… If a Civil War mapmaker simply sketched what he saw or heard about from others, the creeks might be in wrong places, the distances between towns significantly farther or shorter than remembered. Sure, the creek and towns are on the sketch, but the cavalry officer going on patrol might be surprised how long the journey to the objective takes.

This is where science and accurate observation becomes a crucial part of cartography.

A good mapmaker had the tools of his trade and a few tricks for when he was in a real hurry to help him make a scientifically accurate drawing.

First, he carried a compass. A lensatic compass included collapsible sights for setting courses and taking bearings, while still small enough to fit in a coat pocket or saddlebags. At every point along a road or along the route, the mapmaker would stop, take a new heading and note the facts in his book. This ensured the proper north/south, east/west coordinates for his map and accurate placement of mountains, creeks, etc. etc.

Second, he might have had a barometer. The aneroid barometer of that era was round and about ten inches in diameter and could be hauled in a saddlebag or satchel to take relatively accurate measurements of elevation. However, the cartographer or researcher had to keep his eye on the sky; atmospheric changes and storms could affect the barometer’s accuracy.

Third, he had to measure distance with more than visual estimation. Civil War mapmakers would have really loved these exercise apps on modern phones that reveal exactly how far we’ve run. Their methods were more primitive, but still relatively accurate. If the fact finder had time, he would measure distance by surveying chains. If he didn’t have a team, he might use his own measured rope or chain and stretch it along the route he was traveling, haul it in, mark the spot, move farther ahead, etc. etc. Or he could make “scientific estimations.” Knowing the length of his stride, a topographer could figure out how many strides per minute and with that information and a simple mathematical problem figure out how far he went in a certain period of time. But what if he didn’t want to walk 60 miles? Figure out the distance and time equations using his horse’s stride – then start riding and start the pocket watch. While there were drawbacks to the stride method, if a topographer/cartographer knew what he was doing, his range of error was only about 3%.

Use The Pencils and Papers

Returning with his notes or collecting the notes from the topographer, the cartographer got to work on the new map. Using the calculations, notes, and sketches from the field, he drew the new map on study paper. First with pencil, then with pens.

After the penciled map was finished, it would be checked against the notes and any errors corrected. For a more permanent map, when everything was as accurate as possible, the cartographer started tracing his penciled lines with ink, being careful not to smear the wet substance. The ink colors determined which parts of the map got finished first.

One thing that really amazes me about Civil War cartographers is the quality of maps they produced in difficult conditions. For example, Jed Hotchkiss (mapmaker for Confederate General “Stonewall” Jackson) made some of his finest maps, huddling in a canvas tent in pouring rainstorms. That’s crazy! Have you been in a canvas tent during a rainstorm? It’s not easy to keep everything dry…

Use The Production Teams

Once a map was finalized and inked, it went to headquarters or off to the copiers. Either traced by hand, photographed (details here), or prepared and printed by map printers, new copies became available.

One of the challenges for mapmakers was keeping up with changing army locations on their maps. The marks of one day showing the location of friend or foe might not be accurate the next day. For this reason, some map makers at headquarters kept “originals” of the topography maps to make it easier to reproduce the drawings to show new troop positions.

With no Google Maps and only limited maps of regions or states at the beginning of the conflict, mapmakers on both sides employed their observation skills, science, and drawing materials to create new topographical studies which became the roadmaps for campaigns and battles.

Your Historian,

Miss Sarah