I took a lot of history classes in college, and back then one thing history professors liked to say (often!) was that “from the time of the earliest pharaohs to George Washington, information could not travel faster than a horse or sailboat”.
I get the point they’re trying to make… it’s just the assumption is wrong. We know that lighthouses were a thing in antiquity, and they convey information at, well, the speed of light. Smoke signals have been used by armies probably as long as armies have been a thing. Signal flags, too.
By the 1700s, some European powers were building semaphore systems, also known as optical telegraphs. You’d build a series of towers, hopefully on mountains or hills. At the top of each tower was a wooden signaling device (see photo) that could be manipulated into 96 unique positions (characters), depending on the country. Through a series of control characters, they could send messages like “prepare for message”, which would be sent down the line of towers. Much like an electrical telegraph… just, visually.
The British had such a system between the Royal Navy’s base at Portsmouth and the Admiralty in London. The Russians had one between St. Petersburg and Moscow. But the French had an extensive system of 500+ stations spanning thousands of miles; this allowed the French government to send complex messages across the country in as little as 15 minutes. France’s system was so vast that lots of operators were needed, so inventors came up with a set of controls for each signaling system that a single person could easily learn without knowing anything about what he was sending – he’s just copying the symbol shown on the other tower, after all.
Enter François and Joseph Blanc. They were brothers and bankers in Bordeaux. In normal circumstances, it would take around 4 days for stock market information to get from the Paris exchange to Bordeaux. If the Blanc brothers could get the information before anyone else, they’d be able to make millions.
Problem was, the semaphore system was strictly limited to government use only. So they started bribing people. They had a confederate in Paris who, when certain market conditions were met, would send a package via the fastest coach to the telegraph office in Tours. Why Tours? Because it was just south of an “auditing station” outside Paris where all communications were logged and verified.
Inside the package were certain carefully chosen items: maybe a blue dress and black trousers, or a wool cap and a jacket. Perhaps a comb and a towel. The items in the box were the signal to the crooked semaphore operator, who would send a carefully-constructed message to Bourdeaux, but then use the “Oops! Please disregard the previous message” symbol to cancel the message without it being logged into the system. Critically, it wasn’t the content of the message itself, but a particular sequence of specific errors, that made up the secret message.
Lastly, the Blancs paid someone who lived within eyesight of one of the last towers near Bordeaux to spy on it and bring them such messages before they were discarded at the destination.
Their scam went on for TWO YEARS, and the brothers made MILLIONS of francs this way. They only got caught when the corrupt Tours operator fell ill and tried to get a friend to keep the scam going for him. The friend squealed to the authorities, who shut down the ring.
A funny thing, though: by this point, the Blancs could afford better lawyers than the government could, and at trial their lawyers brought up that actually, there were no laws that specifically banned insider trading, nor were there any laws that banned manipulating the official government optical telegraph network. In fact, the only crime the government could pin on them was bribing the operator in Tours. They paid a small fine for this and went on their merry way, only slightly less wealthy than before.
The Blanc brothers died rich, and as a result of their court case, France not only explicitly made hijacking the telegraph system a crime, they also made it illegal for anyone else to set up their own system… which seems a bit much to me.