Fort Bulette, originally Bulette Mineshaft, was a platinum mine manned by dwarves, one of many like it in the Vakil Mountains. It had run dry and fallen into disuse by the beginning of the Futuristic Revolution (299 YD-312 YD), Bradamante's advance on the Confederacy, the Triple Alliance, and the Friends of the Rising Sea (the latter two of which united with Mochizuki-Yamashita to form Ame no Murakami in 301 YD).
As the western theater of the war drew to a close (and formally concluded with the ceasefire of the Ancient Desert, 309 YD), Bradamante's military resolved to commit their resources to the capture of District Vakil. If Vakil fell, a short march downhill would lead to the taking of Futaba and Arakelov, upon which, strategists on both sides predicted, Murakami would collapse.
After an aerial battle forced the evacuation of Base Glenius, the Vakili military, under the General Java Calloni, took a stand at the River Lam-Hai (307 YD), but were driven back into the mountains. From here a five-year siege of the mountains began: Bradamante air superiority prevented the allied air force from lifting the siege and prevented Calloni's host from coming out from underground, but the terrain proved impassible for the Glorious Republic's armies.
In 311 YD, after all contact between the Vakili army and the air force at Base Arimel had been cut off, Calloni ordered Lt. Lavaluka Tutti to lead a party to sneak past the Glorious lines with instructions for a planned liberation. Tutti's party, however, was quickly found and surrounded by enemy forces. Rather than surrender and thus jeopardize the war effort, Tutti took cover in Bulette Mineshaft. After their bullets ran out, the party resorted to makeshift weapons forged from dwarven explosives, training some of the natural monsters growing in the lowest shafts to fight for them, and after their food ran out subsisted on the natural moss which the shaft had been overrun with.
Nine agonizing months later, the war ended and Tutti's party returned to their families as heroes. They had lost nearly half their number, almost entirely due to starvation. The hidden tunnels under Bulette Mineshaft were renamed to Fort Bulette and turned into a national monument, but not swept for mines and other arms.
Who knows what -- or who -- might still be buried deep underground in Fort Bulette, in the tunnels not even Jimkel has explored? Most of the traps are still live, and one of his bots was blown to bits before it even made it down the stairs...