The Solistari War erupted.
The Solistarim took and destroyed Zeif, Ekbir, Tusmit, Ket, Ull, Perrenland, Highfolk, Calrune, half of Delrune, Swantmoor, Veluna, Furyondy, Bissel, Gran March, Verbobonc, the northern Wild Coast, the Shield Lands, and the western two thirds of the Empire of Iuz.
They drove Mordenkainen into exile, and destroyed the dwarven and giant nations of the Yatils. They slew Iuz outright. They besieged Greyhawk City. They devastated northern Keoland and the northern Lortmils and Kron hills.
The Spirit Empire of Garnak, Istivar, Keoland, and great forces from Nippon and Varnaith (Zingia remained neutral) fought back, slew the leader of the Solistarim, and the Solistari assault ground to a halt.
The Solistari withdrew suddenly, each dark race fearing treachery on the part of the other, leaving a vast scoured region of land behind them. A new leader kept the Solistari from launching a new assault, but the southern nations - depleted from the war and not wishing catastrophic losses in the Godspires - did not press the offensive.
What drove the Solistari? Simple. They wanted all that land for themselves. If others held those lands, those others were to be removed. Permanently. There would be no sharing of resources or space. Extermination was required.
Someone pointed out, earlier in this thread, that a dragon could kill thousands of humans and elves. Many dragons allied with the powerful Solistari, came south, and started a kill-fest. Nothing could withstand them, it seemed. Entire cities fell before them, and were burned to cinders and fused rock.
In the east, the Skydwellers attacked, and from their Flying Citadels devastated many parts of the Flannae east.
Unexpected by all, Acererak showed up in Rauxes, slew Ivid, and ascended the Fiend Seeing Throne himself, declaring himself Lord of Aerdi. The Scarlet Brotherhood immediately recognized his overlordship. The yuan-ti followed suit. Messagers from Acererak went to the Thillronian Peninsula, and those Suloise descendents quickly caved and joined the empire.
Most of Aerdi refused to recognize Acererak, as animuses and monstrous rulers everywhere pooled their strength against him. Acererak summoned infernal armies, and human help arrived from both north and south. War raged across Aerdi.
Nyrond and the Urnst nations fomed the Alliance of the Flanaess, in an effort to hold off the storm both east and west. The Adri was absorbed into this alliance.
Meanwhile, the Skydwellers assaulted everyone. Until magical ways were found to blow their citadels out of the sky. After that, they were reduced to raids, their main war effort aborted.
Turrosh Mak took advantage of the confusion to renew his own assault. Celene fell and it's people slain or driven out. The southern Lortmils fell, and Turrosh Mak avenged his people's slaughter of the Hateful Wars. The Duchy of Ulek and the other southern nations were already under attack. Now they had orcs in the mountains to the east.
Finally, once the Solistari had fallen back, the allied nations assaulted this orcish nation. But Turrosh Mak had the help of the scro, and held out against the combined strength of Varnaith, Nippon, Keoland, and the Pearl Empire. After numerous battles and severe losses on both sides, the war was broken off.
Finally, Ahlissa, Irongate, Sunndi, Rel Mord, the Grandwood, central Aerdi, the Sea Barons, and the Lendores were all in Acererak's hands. North Kingdom remained free (it had joined the Alliance of the Flanaess), along with several other northern cities and areas. Acererak broke off the assault and began the reorganization of his new empire.
In the underdark, the drow and the illithid evolved great empires of their own, ignored by those on the surface.
This mess, known as the Solistari War, killed more than half of all the elves in the Flanaess. Highfolk, Celene, and the Lendores were gone. Veluna was in ruins and it's elvish population decimated.
Elven populations elsewhere were depleted as they were forcibly swept up in the war, or sent aid to allies, or were targeted in colossal magical assaults. And after the war, Acererak and the suloise had no use for elves, and enslaved those in their lands. In the Thillronian peninsula, where the people were friendly to elves but allied with Acererak anyways, the elves and humans lived in a detente (both wondering when Acererak would send an edict their way concerning the situation.)
Varnaith and the Pearl Elves were not so badly affected. Both suffered moderate losses only.
But in Delrune, the western half the country had ceased to exist. Half it's people were dead. Perrenland, Highfolk, Calrune, Swantmoor, Veluna, and Furyondy were gone. Only Chauntosbergen remained, and those elves of the Vesve beyond, as organized allies and trading partners.
This situation proved to be both the How and Why of the later Haldendreevan elves. What ended as Haldendreeva, began with this horrific situation in Delrune.