From A Wiki of Ice and Fire
Icemark is a castle along the Wall that has been abandoned by the Night's Watch. To the west lies Hoarfrost Hill and to the east, the Nightfort.
A Clash of Kings
Qhorin Halfhand suggested that Icemark be re-garrisoned to defend the Wall from the wildling horde.
A Storm of Swords
The Weeper was spotted near Icemark during the wildling assault on the Wall.
A Dance with Dragons
Jon Snow re-garrisons Icemark with thirty men twenty from the Night's Watch and ten of Stannis' men. He puts Bedwyck in command.
References and Notes