The last powerful drow leader of the Twisted Tower was the Marshall Azmaer Dhuurniv in its last drow-held days. Azmaer oversaw the last retreat of the drow holdings in the face of a human uprising, and held the citadel against a year-long siege.
The drow rule of Shadowdale lasted until the early 900s Dale Reckoning (-2600 DR until +907 DR, over 3,000 years), when the increased human population in the area brought the dark elves into conflict with their now more numerous neighbors. The humans were the Dalesmen who, a millennium earlier, had crossed the Dragon Reach and made peace with the elves of Myth Drannor, settling at the borders of the great woods that was the elven home. The drow soon found themselves under continual attack, and most of those who held overground settlements retreated back below.
With supplies and slaves brought up from the Underdark directly into the tower, the drow could have conceivably held out forever; However, a human slave (family histories in the Dales indicate a number of possible individuals) poisoned the well in the Tower and the citadel was easily overrun.
Azmaer's body was not found among the dead, leading some to believe that he escaped back into the depths to rejoin his people. Noting the fact that he would have had to explain to the matriarch of House Dhuurniv how he lost Shadowdale, others believe it much more likely that, should Azmaer have survived, he went into voluntary exile, hiding from both human and drow.
However the truth is that Azmaer never truly left his post but rather mummufied himself in spidersilk and waited in undeath for the return of the Drow.