During the Realm Wars Nocton, the god of undeath, made a deal with some of the generals of Hel . They would exchange a portion of the mortal souls they captured during the war to him. In return he would open a portal between Dhodon's demi-plane and the Mortal Realm and unleash the spirits back onto the world. These vengeful specters would then spread out to wreak havoc on the very lands they once tended. The Ghost Council soon learned about this rift and erected The Night's Vigil garrison around the portal. This garrison was solely focused on fighting back the unending waves of undead that would pour from the rift that Nocton created.
Towards the end of the Realm Wars, as Nocton's power began to fade and the demon's steady supply of souls stopped, the Ghost Council was finally able to fight back the inflow of souls and successful in close the rift. The garrison was not disbanded, however, as the threat of the rift opening again seemed eminent. The closing of the rift did, however, give the soldiers stationed there a much needed reprieve and for the first time in centuries the sounds of battle could not be heard from the walled garrison.
While the Spectre's Maw was closed off and the torrent of vengenful spirits was stopped, the barrier between the Mortal Realm and Dhodon's demi-plane was very fragile at this location after years of damage. For this reason the garrison was kept and constantly manned. While not a regular occurance, it was not rare for a few spirits to escape every so often. These incursions were usually swiftly fought back by the garrison who specialised in fighting the undead.
The rift known as the Spectre's Maw was closed.