Once the draugr are dead, the men will go through the door to Korvanjund Crypt. Follow them through and follow the tunnel. You will arrive in a room with multiple bookcases. There are two coffins next to a seemingly dead boss-level draugr sitting on a throne. You can either run up and attack the draugr before he has a chance to attack you, which will let other draugr out of their tombs, or wait for a soldier to go up to the unmoving draugr and mention the crown it wears, at which point the coffins will burst open, revealing hostile draugr.
After they are dead, take the crown from the corpse of the boss draugr. Galmar will tell you to take it straight to Ulfric. If you talk to him again, he will mention that he will stick around for a while to find anything useful. You are no longer required to follow the Stormcloaks. Behind the throne, there is a chest, and at the back of the room there is a [[Skyrim:Word_Wall|Word Wall]] for a word of the shout [[Skyrim:Slow Time|Slow Time]]. Once you have the word, turn around to find a staircase to a tunnel that leads to Korvanjund Temple. Lift the bar off the door and open it, then turn right and head for the exit. Once outside, after descending the second set of stairs, turn around and face the campfire. Beyond the campfire there is a Master locked gate, which is securing a room containing two coin purses and a chest with some nice loot.
Head back to Windhelm and head into the Palace of Kings to give the [[Skyrim:Jagged Crown|Jagged Crown]] to [[Skyrim:Ulfric Stormcloak|Ulfric]]. He will immediately start the next quest, [[Skyrim:Message to Whiterun (Stormcloaks)|Message to Whiterun]]. Alternatively, if you decide that you really want to join the [[Skyrim:Imperial Legion|Imperial Legion]], you can take the crown to [[Skyrim:General Tullius|General Tullius]] in Castle Dour in [[Skyrim:Solitude|Solitude]] and ask to join the Legion. After giving him the crown, he will let you join and you will start the [[Skyrim:Message to Whiterun (Imperial)|next quest]] in the Imperial questline.