The Conflict
Prelude
A great Orc war chief known as Naghat the Brutal, would hear tales from a captured dwarven salve of his time spent in the Underdark, and the vast treasures that lay in the hands of the mighty Drow Matriarchy. This would cause War Chief Naghat to call upon old allies, that being the Ogre Tribe of The Hulking Stuffers and goblins of The Naro Murd tribe would flock to his banner, for the promise of loot and fighting was too delicious to pass up. Flooding an entrance to the Underdark, they would invade in full force.
The Drow were taken by surprise, and in response, albeit struggling to do so, three Drow Houses would form a temporary coalition to fight off this invasion of savage barbarians.
The War Tribes deployment was less organized and more a charging, pillaging tide. The Drow would have to regroup, having their slave axillaries buy them time as they would slink into the shadows. However, the Drow are masters at hitting from hidden cave entrances, and this would prove to be the War Tribes undoing.
Battlefields were less open terrain and alot of cramped, compacted tunnels with a few more open caves to have more traditional style battles.
Conditions were absolutely horrid. Fighting small battles in the Underdark is bad enough when adventuring groups fight one another, but full scale war within tunnels is a nightmare in its own right. Underdark combat is more a massive series of small skirmishes, and using the natural environment as a weapon through creating new tunnels, causing cave ins, and changing the flow of magma. The Drow would largely focus on hit and run warfare and harrying strikes, while the War Tribe would blindly try to blunt force their way through all combat.
However, the Drow would sturggle to commit to any large offensive action, as the Drow Houses would constantly be plagued by infighting and even assassinating some of their personnel in small gambles to weaken the rival house, to further exploit after the war. This would lead to Drow squads being sent in ambushes or suicide missions simply to weaken the other house.
The Drow, while outnumbered, would dance around the invaders. With them assassinating much of the heavy hitting units of the War Tribe, and their baiting strikes and using magma to melt large clumps of enemies, the War Tribe would then charge one last time and besiege the city of Nelhalone. This engagement went better for the War Tribe as it was a far more traditional conflict, and would result in many Drow casualties, however due to their already depleted numbers, would result in a near total massacre of the War Tribe, effectively ending the war in that single battle.
The Drow were quick to enslave all that they could, and of the few that ran away, many would die due to the natural hazards of the Underdark before reaching the surface. With the slaves secured and the War Tribe butchered, the Drow Houses would disband their coalition and largely the status quo would return.
Two of the Drow Houses were significantly weakened by this war, which led the Third Drow House, now known as House Helvilyl, to capitalize on this and entirely wipe their families off the face of the planet.
The War Tribe no longer exists, nor do the Ogre Tribe, having been completely and utterly massacred.
Historical Significance
While this would reinforce the fearsome and ruthless reputation of the Drow, it would also be a very costly war for them. While the total number of dead told by the Drow Matriarchy wasn't too high, that conveniently does not include the amount of civilians killed or the slaves that would try and rebel instead of fight, No official number has ever been able to be confidently made, but if the War is to be of any indication, it must be appallingly high.
Much of the literature of this war has been lost in the Underdark Cataclysm, but a few tomes detailing the conflict, though heavily romanticized, exist in the hands of House Helvilyl