Beacon

Beacons are fires lit on hills or high places, used either as lighthouses for navigation at sea, or for signalling over land that enemy troops are approaching, and alerting the defence. In the latter form, beacons are an ancient form of optical telegraph and always used in relay leagues.

In modern technical parlance, a beacon can also be a radio transmitter used for navigation.

Beacons have often been abused by pirates. A fire at a wrong position was used to direct a ship against cliffs or beaches, so the cargo could be looted after the ship sank or ran aground.