Smoke signal

In ancient China, soldiers along the Great Wall sent smoke signals on its beacon towers to warn one another of enemy invasion.

[3][failed verification] Misuse of the smoke signal is traditionally considered to have contributed to the fall of the Western Zhou dynasty in the 8th century BCE.

Colored smoke grenades are commonly used by military forces to mark positions, especially during calls for artillery or air support.

[6][7] Lewis and Clark's journals cite several occasions when they adopted the Native American method of setting the plains on fire to communicate the presence of their party or their desire to meet with local tribes.

[8] Yámanas of South America used fire to send messages by smoke signals, for instance if a whale drifted ashore.

[11][12] The Cape Town Noon Gun, specifically the smoke its firing generates, was used to set marine chronometers in Table Bay.

[14][15] Different colours of smoke (black, white or blue, depending on whether the material being burnt was wet grass, dry grass, reeds or other materials) were used to convert information, as was the smoke's shape (a column, ball or ring), allowing a messaging system sophisticated enough to include the names of individual tribesmen.