During
the Napoleonic Wars, the French revolutionized land-based communications with
the erection of semaphore towers bearing rotating arms to fashion coded signals
that could speed by line-of-sight from tower to tower along the coast and
across the country at some 200 miles an hour.
The British quickly followed suit in that new era of signals
intelligence. Theft of the enemy’s
semaphore codebooks became an important part of the business of war.