History Behind Semaphore Flags

Optical “telegraphs” or signaling devices have been traced back to ancient times (using torches) and were the fastest systems to convey messages over long distances. These “telegraphs” could have since been in the form of torches, smoke signals and eventually semaphore towers.

Semaphore towers used large blades/paddles to convey messages. These messages were decoded based on the fixed positions of these arms and could transmit signals up to 150 miles in two minutes using multiple towers.

The semaphore tower/semaphore line design was first thought up by Robert Hooke in 1684 and submitted to the Royal Society. The system was not implemented though due to military concerns. However, this did lead to Claude Chappe developing the first visual telegraph in 1792 – eventually covering much of France via 556 stations. In France, this was the primary source of communication for military and national applications, until it became more widely used in the 1850’s. Designs varied between using shudders open and closed to holes being open and closed, but Chappe’s design became the most widely used semaphore design.

Chappe’s design used large towers that had a single crossbar with large pivoting “arms” at the ends and were spaced as far as part as the eye could see. The crossbar could be used in 4 different positions while the arms could be in 7 different positions each, for a combination of 196 (4x7x7) characters. These 196 characters could be combined to create a multitude of messages and phrases. Some have estimated that there were as many as 9,999 different “codes” created.

Many other takes of semaphores became created, including the naval signaling code flags which are still used today. These flags could be used in combination to become different words and messages and thus not have to spell out each word since messages were usually needed to be displayed quickly. This system however proved to be slow during battle since these flags were hoisted to the top of the ship for display.

Even Napoleon used one design to communicate to his army strategies and locations of his enemies. These semaphore stations were so successful that the French government rejected Samual Morse‘s first proposals of the electrical telegraph, citing that its design was flawed by wires being able to be cut easily.

These visual messaging systems eventually led to semaphore flags. These flags were used in the same way that the arms were used on the semaphore towers – different fixed positions mean different messages. Semaphore flags were primarily used for naval applications to communicate message between boats. It proved to be a very useful tactic during battles, most famously the Battle of Trafalgar during the Napoleonic Wars.

Today these flags have become smaller and are usually mounted to small dowels or poles to allow them to be seen easier. Maritime use flags are red and yellow (or the OSCAR) flag and while in land use, the flags are blue and white (or the PAPA) flag. Even though they are not in use much anymore, they still serve for some boats and ships.

So why did we get rid of them?

Well, there were two critical downfalls of all the systems:

  1. They had no secrecy. Everyone within visual distances could see the message and therefore react to it. This proved to be one of the design’s most fatal wartime attributes.
  2. They were practically invisible at night time and during heavy fog and rain.

Both of these reasons lead to the electrical telegraph and Morse Code, both “invented” by Samuel F.B. Morse.

So, the next thing you know, we went to electrical telegraphs, pony express, telephone, radio, television, computers, fax machines, satellite televisions, cellular phones and the internet. What is next to come in communication? I for one can not even begin to imagine all of the amazing devices we will see in the future. The one thing I do know is that ultimately semaphore flags and towers inspired all designs since. To see how basic letters are signaled with semaphore flags, please check out this video:

One Response

  1. The bit of semaphore flag history that would interest me is, why are J and Y completely out of sequence and why are Y, Annul, Numeric, and J inserted between U and V, completely breaking up the rather neat clock type arrangement, and making it harder to learn. Does anyone know?

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