How were maps and war plans duplicated during the Civil War? Was it different between the Union and the Confederacy? If it was, what impact did it have on the outcome of battles/ the war?
I've been going through documents on the NARA website, researching the application of photochemical processes in the duplication of maps. The Union seems to have developed a contact printing method for mass replication of maps on pre-salted papers, which were purchased from E and HT Anthony's in New York City.
Later in the war, they started using CC Harrison's Globe Lens to scale down the maps and plans. Prior to that, they were experimenting with orthoscopic lenses, but those yielded unreliable results. It wasn't until the introduction of the Globe lens that they could be accurately replicated. The letters put particular emphasis on the importance of accuracy in nautical maps because of the bathometric data.
I've read that the Confederacy relied on hand copying maps, but I question the veracity of that claim. They would have had the ability to duplicate them with lithography at least, which was costly and a bit time-consuming, but not nearly as time-consuming as hand copying each map.