(Coming up from here.)
The messengers ride south from Amon Ereb to the secluded isle of Tol Galen, in the peaceful Land of the Dead that Live.
They return un-heard, harried by Ents from the deep forest. Luthien the Nightingale will have no truck with the children of Feanor.
But Maedhros is properly spooked, and not inclined to give up. His next messenger isn't a member of his House - it's you, a mortal, and Beren is willing to listen out of sheer curiousity.
It takes a while to get your point across. Your Mysterious Voice from Above has to feed you lines of broken Sindarin, until Beren and Luthien manage to teach you enough to get along. You spend a full year in Dor Firn-i-Guinar. But ultimately, they agree.
Messages crisscross Middle-earth, guided by your knowledge of the usurped future. At Luthien's urging, Thingol sends forth the armies of Doriath for the first time, clearing Beleriand proper of orcs for a time. With that breathing space, you are able to direct the growing Embassy (as the group seeking to send a message to the Valar becomes known) to Nargothrond and even into Gondolin - much to the shock of Turgon, until you remind him that the true hope of the Noldor lieth in the West, and cometh from the Sea.
Mountaineers from the Hidden City cross the passes into Dor-lómin, where they rescue as many of the mortals of Hador's house as they can find. Tuor, only a year old, is brought to Doriath, and meets for the first time his cousins Turin and Nienor. Until her children and nephew reach a suitable age - or until her husband is rescued - Morwen Elfsheen takes on the leadership of the Third House. (She is, incidentally, starstruck to meet her cousin Beren - though much too staid to show it.)
On the Isle of Balar, Cirdan is set to build a dozen ships - but you rightly point out that only the Silmaril can guarantee passage to Aman. Only one ship is needed - and its passengers are more important than its structure.
The planning takes ten years. Morgoth does not remain quiet, but pushes into Beleriand again, knowing his enemies are planning something but not being sure what. Turin gets into his share of mishaps. Gondolin comes under siege. Brethil, home of the Second House of the Edain, is partially conquered, but holds firm with the aid of their golden-haired kin. Curufin and Caranthir make an abortive effort to steal the Silmaril, but are stopped by Maedhros and imprisoned.
At last the ship departs. Its premier passenger is Dior, son of Beren and Luthien, the only half-elven in the world; he bears the Silmaril, bound on his brow. The other passengers and crew represent the blameless youth of the many kindreds of Beleriand: Turin for the Third House, Brandir for the second; Celebrimbor for House Feanor, Idril for House Fingolfin, Gil-Galad son of Orodreth for House Finarfin; Nimloth, great-niece of Thingol, for the Sindar; and you.
The ship sails for weeks across the unnaturally-calm sea, the light of the Silmaril guiding its path, and comes clear through to the shores of Faery. You warn Dior, Brandir, and Turin that if they set foot in the Undying Lands, they may never be allowed to return to the mortal realm. Brandir listens to you. The others do not.
Leaving the heir of Haleth to watch the ship, the seven of you trek inland. You do not enter Alqualonde or Tirion, though the gates stand open, and awestruck faces watch from the walls as you pass. You enter the heart of Valinor, and come at last to the Ring of Doom.
You, personally, say nothing in the presence of the Valar, averting your eyes from them as your companions present their case. You sense the thoughtful gaze of Manwe Sulimo, the Elder King, boring into you, but he does not address you.
The Embassy's pleas are met with approval by the Powers. A Great Armament begins in Valinor. Contrary to your expectations, it is not Dior and Turin who are told they can never return home, but Celebrimbor. Though guiltless of the Oath, he has still violated the Ban on his House - and as punishment for his transgression and reward for his bravery and honesty, he will be sent into the heavens with the Silmaril, as a guard against the Void and a message to the Free Peoples.
The Host of Valinor takes three years to muster. Then it sails on Middle-earth, with the remnants of the Embassy in the foremost ship.
The War of Wrath is actually less destructive - and shorter - than in the unchanged timeline. The Host does not have to fight its way north from its very landing, but can march almost to the Pass of Sirion before coming to the territory held by Morgoth. With the hosts of Doriath, Nargothrond, Amon Ereb, and the Edain joining them, they break the Siege of Gondolin and march forth onto Anfauglith.
Some things go badly. At one point, trying to broker peace, Morgoth brings forth his highest-profile prisoners - including Gwindor of Nargothrond, and Hurin Lord of Dor-Lomin - and promises to free them if the Valar will depart. His offer is flatly denied, and their loved ones are forced to watch as the prisoners are massacred. From that point on, Turin (taking the name Acharn, 'the Avenger', and wearing the Dragon-Helm of Dor-Lomin) is a force of destruction on the battlefield. It is he who brings down Glaurung the Golden, and he - with the aid of multiple others, including a last-minute rescue from Celebrimbor and his ship - who destroys Ancalagon the Black, Morgoth's not-quite-mature superweapon.
The war comes to an end: Morgoth is taken captive and cast out. Southern Beleriand still stands above the sea, though it is bounded now by ocean to the north as well as the south. The ancestral homes of the Edain are all destroyed, so Numenor is still raised as a land for all three kindreds. Though the Valar intend Dior to take the kingship, by popular acclaim Turin is appointed instead - and to equally popular acclaim, he makes sure that his mother is recognised officially as First Ruling Queen, predating him on the throne. (At nearly 70, Morwen doesn't want to actually rule, but definitely appreciates the prestige.) Ultimately, Numenor is a peaceful and happy land, though in later years it develops a disturbing tendency towards near-kin marriages in the royal house.
The Ban is lifted, allowing the Noldor to return to Aman. Most of them choose not to. With Nargothrond and Gondolin still standing (though the latter is almost entirely surrounded by water), and even Himring still inhabitable, many of their people remain in Beleriand. Others migrate east (including Galadriel, who still chooses to set up shop in Eregion). Of all the Noldor of Finwe's line, only Maedhros himself chooses to journey into the West, accompanying the remaining two Silmarils and watching over them as they are laid to rest at the foot of the Two Trees whose light they bear.
As for you: the world is at peace. Morgoth is banished, Sauron fled, the Orcs and other works of evil scattered to the distant mountains. You can go anywhere in Middle-earth that you choose - but of course, we already know where you're heading.
The dwarves of Belegost aren't much interested in talking to you at first. But you'll bring them round.
You always do.
I love the Alternate History parts. ^_^ I apologise for all the jabs at Turin, but to be honest he deserves it.
The Embassy (F.A. 483)
Dior (age 13) - Peredhel, First House
Brandir the Lame (age 18) - Second House
Turin the Less Hapless (age 19) - Third House
Celebrimbor - House Feanor
Idril - House Fingolfin
Gil-Galad - House Finarfin
Nimloth - Sindar
& You
The Lords of Beleriand (F.A. 486, the landing of the Host of Valinor)
Maedhros of Amon Ereb
Thingol and Melian of Doriath
Orodreth of Nargothrond
Turgon of Gondolin
Cirdan of the Havens
Turin/Morwen of the House of Hador (in Doriath)
Handir of the House of Haleth (Brethil)
Beren and Luthien of Dor Firn-i-Guinar
Dwarf-lords of Nogrod & Belegost
hS