First I'm to meet the party outside Fort Dunstead, then take it over... one huge problem: No one is there including the Stormcloaks I am supposed to meet.
Only thing I found in the Fort are two horses (in which I killed) and a completely empty interior.
I assumed maybe the quest was a joke or I needed to find an item instead...but there is nothing there at all.
Maybe the main quest bugged it? During the negotiation at the Graybeards, the Pale was a subject...Ulfric did say he didn't forget about it, but idk.
If I'm missing something, let me know... I did go around to other areas Imperials were at and try killing them instead, but that didn't work.