Dailan was a dwarf who was a leader or in charge of the last stand of Kal'Hirol. He is most notable for convincing some two hundred casteless dwarves to assist in the suicidal battle. The final days of Kal'Hirol and Dailan's impact on events can be witnessed in Dragon Age: Origins - Awakening by The Warden-Commander.
Last Stand of Kal'Hirol
During the First Blight, several thaigs were overrun by darkspawn. It became clear that Kal'Hirol would soon be one of them and evacuations were prepared. Within days, however, it was realized that there would be no time to plan and the evacuation took place without warning. Dailan volunteered to be part of a group that remained behind to hold the encroaching darkspawn back, giving the refugees a chance to flee to Orzammar.
Two days after the evacuation, Dailan realized that around five hundred casteless dwarves had been abandoned. Dailan, feeling that the guard would fail, proposed to the casteless that they join with him in the suicidal battle, and attempted to galvanize them by suggesting they prove they are not as worthless as dwarven society claimed. Despite opposition amongst some of the casteless, approximately 200 volunteered for the duty. It is not known what happened to the others though at least a few attempted to find a route to the surface.
The army held back the darkspawn for five days, inspiring Dailan to stop using the term casteless to refer to his comrades-in-arms. Inspired, Dailan felt it imperative to record the names of all who stood as part of the defense Kal'Hirol, being slain by an ogre as he finished.
Involvement
In Awakening, the Warden-Commander can find the stone marker on which are recorded the names of those casteless which defended their homes to the last breath. Finding the tablet triggers the quest Memories of the Stone in which the Warden-Commander can pass the marker to Dworkin Glavonak and his brother Voldrik Glavonak. It is revealed in the epilogue that the brothers delivered the record to the king of Orzammar. House Helmi led a great army of dwarves and reclaimed Kal'Hirol, where a ceremony was held to commemorate and honour the sacrifice of Dailan and the casteless.