Siege of Menzoberranzan

The Siege of Menzoberranzan was a siege of the drow city of Menzoberranzan by the combined forces of Horgar Steelshadow of Gracklstugh and Kaanyr Vhok's Scoured Legion with the secret backing of the Jaezred Chaulssin.

Slave uprising
During the Silence of Lolth, which began on Eleint 28, 1372 DR, the goddess Lolth did not answer any of her supplicants, nor were her clerics able to cast any spells or otherwise use divine magic. Menzoberranzan, a matriarchal order ruled by Lolthite priestesses, was naturally in a perilous position. Priestesses were ordered by Matron Mother Triel Baenre not to speak of the Silence, but word nevertheless got out. A group of renegade male drow, led by the alhoon Syrzan (likely with support from the Jaezred Chaulssin), instigated an uprising of slaves and "undercreatures" on Marpenoth 20. This group, which used stonefire as a weapon, damaged the city and forced the slaughter of a large number of slaves.

Battle of the Pillars of Woe
Soon after the slave revolt, the leaders of Menzoberranzan received word (via Nimor Imphraezl of the Jaezred Chaulssin, who was posing as the drow captain Zhayemd of House Agrach Dyrr) that Crown Prince Horgar Steelshadow had amassed a duergar army that was marching against the city. Nimor's warning instigated the creation of the Army of the Black Spider, a conglomeration of soldiers and slave fodder from two dozen drow houses. The army marched out to the Pillars of Woe, where they were ambushed by the duergar, who were joined by the tanarukks of the Scoured Legion. In addition, the contingent of House Agrach Dyrr turned on their fellows, Matron Yasraena Dyrr and the Lichdrow Dyrr having made an alliance with the Jaezred Chaulssin. The drow army lost a fourth to a third of their total number (which had been 4,000 drow and 2,500 slaves ) and were forced to retreat under cover of a rescue contingent sent by House Baenre.

Siege of Menzoberranzan
On Uktar 3, 1372 DR, Kaanyr Vhok and the forces of Gracklstugh (more than 5,000 duergar in more than eight companies, with orc and ogre slaves ) began besieging Menzoberranzan itself. The forces approached from the southeast,and also swung around and attacked from the north, utilizing a tunnel from outside the city that gave access to Tier Breche where the Academy was located. This remained the main battlefield for quite some time, which the masters of the Academy working together to prevent the besiegers from overtaking the city. The attackers used stonefire to damage the Academy's structures; they were damaged but remained intact at the end of the siege. In addition, the duergar armies raised undead soldiers to fight from them. At least once, the Archmage of Menzoberranzan was able to turn the undead soldiers against their fellows.

Just before the siege began, Gromph Baenre, the Archmage, had been missing for a period of several weeks after being imprisoned by the Lichdrow Dyrr. He returned to find the city under siege and he took it upon himself to remove Nimor Imphraezl from the picture. He gathered all the mages of House Baenre and attempted to attack Nimor through a scrying crystal. However, Nimor's protections reflected the spells cast upon him, killing Julani Baenre and injuring the other wizards. Gromph then disguised himself and weaponsmaster Andzrel Baenre as tanarukks of the Scourged Legion and entered the enemy camp. Gromph attached a light gem to Nimor to prevent him shadow-walking. Nimor transported himself to the Plane of Shadow, but was stuck there for some time, unable to shadow-walk back to the Material Plane.

At the same time that the city was besieged by outside forces, House Xorlarrin, with some support from other houses, was besieging the traitorous House Agrach Dyrr. Gromph Baenre also confronted the Lichdrow Dyrr in a spell battle that destroyed the Bazaar. The Jaezred Chaulssin also attempted an assassination attempt on Triel Baenre, which failed.

On Ches 28, 1373 DR, the Silence of Lolth ended and Lolth's priestesses regained their powers. Kaanyr Vhok subsequently recalled his forces to Hellgate Keep; the remaining duergar were easily defeated and turned back. The siege officially ended on Ches 30.

Aftermath
All in all, Vhok lost 120 tanarukks in the Siege of Menzoberranzan. There was an unknown -- but surely much greater -- number of duergar, drow, and slave casualties.

As the duergar army retreated, Nimor swept in and killed Horgar Steelshadow. He spoke with Vhok, ensuring that the Scoured Legion and the Jaezred Chaulssin could still be potential allies in the future.

Soon after the siege had ended, life in the city had mostly returned to normal. The inhabitants were in the process of rebuilding the damage with the help of the captured duergar, which had become slaves.

House Agrach Dyrr was spared, except for the temple, which was destroyed when Gromph Baenre inadvertently activated the master ward while destroying the phylactery of the Lichdrow. Triel Baenre arrived and halted the Xorlarrins' assault, meeting with Anival Dyrr and forming an agreement: House Agrach Dyrr was to become a vassal of House Baenre for centuries, "essentially an extension of House Baenre."