|Theater of operations|
Bael'dun is a group of dwarves sent by the Explorers' League to Kalimdor in order to make archaeological excavations. While setting up Bael Modan, the dwarves attacked the local tauren living there, who were displaced and forced out for allegedly being a nuisance to their digging. The dwarves later increased their military due to dealing with various rogue elements, and were thinking of asking the Alliance army to establish a military presence in the area as it was also of strategic importance.
The group is separated in two parts - the scientific and the military one. The scientific branch under Prospector Khazgorm cares for the excavations, while the military branch, led by General Twinbraid secures the digsites and fights intruders. Therefore the dwarves built Bael'dun Keep and stationed a flying machine there. They have two known digsites, Bael Modan in the Southern Barrens, and the Bael'dun Digsite in Mulgore.
World of Warcraft
This section concerns content related to the original World of Warcraft.
Bael Modan was once a part of the lands that served as home and provider to the Stonespire tribe. Then the dwarves came and began their excavation operations, forcing the tauren out and killing many innocent who opposed. Prospector Khazgorm's own journal says they drove out the tauren because they were being a nuisance to the operations, as for the dwarves it was more important their work than the "comfort of the local inhabitants". Not only that, but Bael Modan's strategic position might be of value to the Alliance.
The tauren tried to approach the dwarves of Bael'dun to reach a diplomatic resolution but it failed. Tired of waiting and angered about his people's persecution, Gann Stonespire sent a Horde champion to reclaim the journal of Prospector Khazgorm and retaliate against the dwarves, killing Khazgorm in the process. After gathering supplies to make explosives, the champion was tasked do use them to destroy a flying machine to show the dwarves a lesson. 
Here the dwarves use heavy explosives to break through even the most dense masses. During their excavations, they found the , an ancient artifact, but General Twinbraid locked it away. Feegly, exiled for becoming obsessive and trying to use the Tear, retrieve them with the help of a Horde champion.
In Mulgore, the Bael'dun Digsite is a small excavation operation west of Thunder Bluff. They disregarded the pleas of Baine Bloodhoof who said it was angering the spirits of the earth. He sent his people to steal and smash the dwarven tools in order to stop them.
This section concerns content related to Cataclysm.
During the Alliance offensive against the Horde settlements in the Barrens, Camp Taurajo was destroyed and other areas occupied by the Alliance military. Gann Stonespire was one of the mortally wounded. During their last raid to Bael'Dun Keep, Gann and his party managed to smuggle a goblin saboteur inside: Weezil Slipshadow. An Horde champion was sent to assist him. After finding the plans of the keep and location the ammunition room, the two sabotaged the artillery shells and tried to escape while the keep was destroyed in the explosion. Although the adventurer survived, Weezil did not.
Sometime before the destruction of the keep, General Twinbraid, who was scouting the Barrens, sent an Alliance adventurer to the excavation site at Bael Modan. There the adventurer was met by Twinbraid's son, Marley. The dwarf sent him to finish off Feegly the Exiled, who had turned into a trogg after so much contact with the Tears of the Moons. Afterwards, the Horde raid Bael Modan. The champion defended the excavation site while retrieving artifacts and helping Marley repair his own flying machine. The two got onto it, tried to fly back to General Twinbraid, but were struck down near Bael'dun Keep after the keep's explosion. Not long after Marley died. Despite the loss, several Bael'dun Survivors were rescued.
General Twinbraid heard the bad news and stated this time the Horde had made things personal. After finding out a goblin corpse inside the ruined fortress, they mistakenly came to the conclusion it was the Bilgewater Cartel who did that. Raging with vengeance, Twinbraid sent the Alliance champion to Frazzlecraz Motherlode, a Bilgewater goblin mining operation not far from Bael Modan. There he was tasked in killing some mine workers, and bury the rest alive. Although Twinbraid was happy to hear the news, the champion knew this wouldn't be enough to quench his thirst for vengeance.
Battle for Azeroth
This section concerns content related to Battle for Azeroth.