Bag om Past Wars and Tactics
Maps can be useful in war, but many of the things they are helpful for can be achieved by other means, at least to an extent. An ancient or medieval commander wouldn't have an accurate map of the land he's campaigning on, but reconnaissance could help him learn about it. He might not have a map of the battlefield he was fighting on, and if he did, then it would probably be very primitive, but again reconnaissance could help him learn about it. He probably wouldn't have a map to help him keep track of troops who were outside his visual range and, again, if he did, it was probably pretty primitive. Still, he'd be able to contact them with trumpets, drums, and couriers, and armies were more compact back then, so they wouldn't be that far away. I still think ancient, and medieval armies would have used maps if they were available after all if a tool is available that can help you win, then why not use it?
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