Today I learned
That the precursor to the electric telegraph was the optical telegraph, also known as the semaphore.
A mechanical signaling system placed high up on top of towers, chained together to other stations up to 10km away.
This was a real thing.
Napoleon’s France used it for communicating military and private matters. A single character message from Lille to Paris could take as little as ten minutes. It even served as a crucial plot piece in the Count of Monte Cristo, when disinformation spread by the protagonist lead to the financial ruin of his enemies.
These bring to mind earlier networks that use fire. Used by the Chinese, Romans, et cetera, and fictionally in The Lord of the Rings, these could only send a single bit of information. As a result, they were used for the highest priority information: early warning.
Thank you to Brian Kernighan and his book D is for Digital for the education.