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Optical “telegraphs” or signaling devices have been traced back to ancient times (using torches). It was the fastest system to convey messages over long distances.
The semaphore signaling system was designed by Claude Chappe, a French engineer, in the late 18th century. The first semaphore line was established between Paris and Lille in 1793. Then it was adopted to carry despatches between French army units, including those commanded by Napoleon.
Semaphores were adopted and widely used with hand-held flags in the maritime world. Today, the semaphore system uses flags, usually square and divided diagonally into a red and a yellow section with the red in the uppermost triangle. The flag in each arm can be held in eight different positions with the combination of two flags used to represent letters, numbers, and symbols.