Oakenshield is one of the abandoned castles of the Night's Watch, standing upon the Wall a short march east of Castle Black. Its garrison was withdrawn long ago as the Watch's numbers failed, though its nearness to the black brothers' chief seat has kept its ruin gentler than most.
In Castle Black's Shadow
Of the nineteen castles of the Wall, those closest to Castle Black were among the last to be emptied, and Oakenshield's keeps still stand where remoter castles have crumbled. Its gate is sealed and its hearths cold, but patrols from Castle Black walk the ice above it, and of all the empty castles it would be among the easiest to garrison anew.