Grim Batol was the former dwarf-hold of the Wildhammer Clan, situated on the border between the Wetlands and Northeron. Destroyed and cursed during the War of the Three Hammers, the thrice cursed fortress has since changed hands several times over to various factions and borne witness to unimaginable horrors with seemingly no hope of cleansing.
Founding and War of the Three Hammers
The great dwarven city was founded after the Wildhammer Clan lost in a great civil war between the three main dwarven clans: Themselves, the Bronzebeard Clan and the Dark Iron Clan. Led by High Thane Khardros Wildhammer, they made their way north, into the mountain that would share its name with the city. Over the years, the Wildhammer clan would carve a vast and mighty fortress-citadel and home into the northernmost ranges the Mountains of Khaz'goroth.
Years later, Sorcerer-thane Thaurissan of the Dark Iron clan sought vengeance against the other dwarven clans. From the city of Thaurissan, in the northern part of the Redridge Mountains that would later be named the "Burning Steppes", he led his forces to the city of Ironforge, while his wife Modgud led the forces attacking Grim Batol.
Although the Bronzebeards managed to hold Ironforge and push back the attackers, Modgud's forces were starting to break through. Calling shadows to attack the Wildhammers, the Dark Iron sorceress' forces continued their assault, until Khardros broke through the Dark Iron lines and killed Modgud in single combat.
Now finding themselves leaderless, the Dark Irons started to retreat towards Redridge, but were intercepted by the Bronzebeard army that was on its way to aid the Wildhammers.
After the final conflict of the war, the Wildhammers returned to Grim Batol to find that it had been cursed by Modgud's dying curse. It was tainted, uninhabitable. Although the Bronzebeards offered to let the Wildhammers return to Ironforge, they declined, preferring to found a new home in the Aerie Peaks of the Hinterlands.
During the Second War, Grim Batol was occupied by the Orcish Horde and became one of their primary bases, used for its oil refining operations and headquarters of their naval forces. More important to the Orcish war effort however, was the presence of Alexstraza, the Lifebringer.
The Dragonmaw Clan had imprisoned the Red Dragon Aspect within the mountain fortress and held her captive, forcing her to give birth to other red dragons that were used as mounts by the orcs using the Demon Soul. The Dragonqueen was held prisoner within the fortress throughout the entirety and aftermath of the second war, adding to the fortress's already black reputation.
After Orgrim Doomhammer and the Horde's primary force was defeated at the Battle of Blackrock Spire, The dragon queen was freed by a band of adventures consisting of the mage Rhonin, future leader of the Kirin Tor, Falstad Wildhammer, future High Thane of the Wildhammer Clans, and the Quel'dorei Ranger Veressa Windrunner. Immediately after being freed, Alexstrasza set out about destroying every single orc she could find, beginning with their leader, Nekros Skullcrusher, who she ate whole.
Post Third War
By the time of the end of the Third War, Grim Batol remained sealed and guarded by the red dragonflight, led by one of their champions, the red drake Axtroz. While being relatively peaceful, Axtroz was killed during the chain of events that would eventually lead to the death of Onyxia, the black dragon broodmother.
Shortly before the War in Northrend, Grim Batol placed host to a new generation of atrocities. The Black Wyrm Sintharia, Prime Consort of Deathwing the Destroyer, took residence in the Fortress along with her large bounty of stolen Dragon eggs, harvested across millennia and preserved in magical fluid. Using the innocent dragon eggs and stolen energies of the unique Nether Dragons, as well as tampering from Blue Dragonflight relics and the energies of a stolen Naaru staff, Sintharia created a deadly concoction which gave birth to the very first generations of the Twilight Dragonflight.
Sintharia and her creations were eventually undone, thanks in no small part to the Red Dragon mage Krasus and again the faithful assistance of Rhonin Redhair and Veressa Windrunner, but the research conducted within the increasingly accursed fortress was harvested by the hand of Deathwing himself, who would salvage her materials and continue research into the clutch of Twilight Dragons.
After the Cataclysm, Grim Batol was seized by agents of the Cult of the Twilight's Hammer, who used much of Northeron, now more commonly known as the "Twilight Highlands", as their base of operations. The red dragon defenders were driven away from the fortress gates and the dwarven fortress was used as a training ground and mighty stronghold for the black dragon aspect's followers. Many of Alexstraza's eggs were left behind by the Dragonmaw Orcs and Sintharia's experiments, and several were corrupted into Twilight dragonkin.
Grim Batol was eventually freed attacked repeatedly by the Red Dragonflight and the shamanistic Earthen Ring, seeking to put an end to the fortress's legacy of evil. The twilight dragon commander General Umbriss and his other subordinates under him killed during an attack, and the C'thraxxi corruptor behind the creation of Twilight Dragonkin within Alexstrasza's former cell was destroyed, and the vast majority of Twilight's Hammer cultists were slaughtered by the thousand.
Grim Batol saw one more use by elements of the Dragonmaw Clan in the aftermath of the Siege of Orgrimmar. While Garrosh Hellscream was on trial in Pandaria, the True Horde Warlord Zaela and a small handful of Dragonmaw followers made the Fortress a hideout whilst they schemed on how to free their deposed Warchief. The Hellscream loyalists were approached by an unexpected offer of aid by the Bronze Dragon Kairozdormu, and the Infinite Dragonflight of which he had allied himself with. Zaela accepted the Bronze Dragon's terms, and the Hellscream loyalists departed the fortress, leaving Grim Batol to this day, as silent and still as death.