”Using fire to signify a message is thousands of years old. The earliest use of beacons in the UK dates back to the medieval period, primarily as a means of communication to warn of impending invasions or other dangers. Positioned on hilltops and along coastlines, these beacons were part of an early warning system signalling the presence of a threat, such as an approaching enemy fleet.
One of the most famous early examples is the network of beacons used during the Spanish Armada in 1588. As around 150 Spanish battleships approached, beacons were lit along the southern coast of England, from Cornwall to London. As a result of this rudimentary but effective system Lord Francis Drake had the time to mobilise the country’s defences and defeat the Spanish fleet before they were able to reach the English shore.”
[1] https://www.paintersforstal.co.uk/news/the-history-of-beacon...