I was wondering if lighting fires across long distance for alerting or messageing really happened? Not like smoke signals, but across mountain ranges or long plains to alert to invasion.
I don't know about mountain ranges and plains Lord of the Rings style, but the English used beacons up and down the coast for this purpose - and quite recently too.
Prior to electricity and the earliest forms of communication that came with it, a simple message that needed to be sent quickly over a vast distance couldn't be done easily. A more complex message obviously would need to be conveyed in writing or by word of mouth, but for something like "Under attack!", there were simpler options, like beacon fires.
England, being an island nation with multiple threats from the continent, often had to be aware of naval invasions. At the time of the Spanish Armada, the fear of Spanish invasion was huge, and the Privy Council ordered that bales be prepared on certain hills in Southern England so that in the event of invasion, they could be lit.
The same thing occurred during the wars with Napoleon, at the beginning of the nineteenth century, this time with beacons lining the coast of Scotland as well.
Afterthought: logically, beacon fires are the same thing as lighthouses - just warning of different dangers. The Lighthouse 'Pharos' of Alexandria was built c. 280 BC, so it's not a big leap from there to conclude that beacon fires were being used in the intervening millennium to warn of danger.
Source: Northern Notes and Queries, an old Scottish journal from 1890. It references the Registers of the Privy Council (vol. i. p. 73) as the primary source info for this.
I can't provide an example of a specific historical case, but the following passage in Aischylos' Agamemnon, lines 280ff., attests to the idea of a chain of beacons in a play dating to 458 BCE.
The play is set just after the Trojan War; the beacons transmit word from Troy to Argos to tell Klytaimestra -- the wife of Agamemnon, the leader of the Greek forces -- that Troy has fallen. Translation by Herbert Weir Smyth, 1926.
CHORUS. And what messenger could reach here with such speed?
CLYTAEMESTRA. Hephaestus, from Ida speeding forth his brilliant blaze. Beacon passed beacon on to us by courier-flame: Ida, to the Hermaean crag in Lemnos; to the mighty blaze upon the island succeeded, third, the summit of Athos sacred to Zeus; and, soaring high aloft so as to leap across the sea, the flame, travelling joyously onward in its strength the pinewood torch, its golden-beamed light, as another sun, passing the message on to the watchtowers of Macistus. He, delaying not nor carelessly overcome by sleep, did not neglect his part as messenger. Far over Euripus' stream came the beacon-light and signalled to the watchmen on Messapion. They, kindling a heap of withered heather, lit up their answering blaze and sped the message on. The flame, now gathering strength and in no way dimmed, like a radiant moon overleaped the plain of Asopus to Cithaeron's ridges, and roused another relay of missive fire. Nor did the warders there disdain the far-flung light, but made a blaze higher than their commands. Across Gorgopus' water shot the light, reached the mount of Aegiplanctus, and urged the ordinance of fire to make no delay. Kindling high with unstinted force a mighty beard of flame, they sped it forward so that, as it blazed, it passed even the headland that looks upon the Saronic gulf; until it swooped down when it reached the lookout, near to our city, upon the peak of Arachnaeus; and next upon this roof of the Atreidae it leapt, this very fire not undescended from the Idaean flame. Such are the torch-bearers I have arranged, completing the course in succession one to the other; and the victor is he who ran both first and last. This is the kind of proof and token I give you, the message of my husband from Troy to me.
Unfortunately the geography here is pretty rotten in one or two places -- e.g. Lemnos is too far from Mt Athos for that step in the chain to work -- and some of the placenames are now unknown.
hi! you may be interested in these previous posts
not quite the same thing, but still signals using fire