Skyrim:Rescue from Fort Kastav

Quick Walkthrough
# Report to Legate Rikke at Winterhold Imperial Camp.
# Meet the Imperial scouts near Fort Kastav.
# Sneak into Fort Kastav.
# Free the prisoners from their cells.
# Clear the fort of Stormcloak soldiers.
# Report back to the scout team commander.

Detailed Walkthrough
Report to Rikke
Report for duty to Legate Rikke at Winterhold Imperial Camp, east of Dawnstar. 

She will tell you to take Fort Kastav from the Stormcloaks. 

As the rebels currently hold some fellow Legionnaires in the fort's prison, you are to meet up with some scouts in the area, infiltrate the prison, release the prisoners, and then use their help to take the fort from the inside.    

When you agree to take the mission, the quest will initiate. Rikke will mark the scouts' location on your map (southeast of your location, about halfway to Windhelm), and you will note in your journal that your objective is to "Meet the men near Fort Kastav".

You can successfully complete the quest without first sneaking inside and freeing the prisoners, but to accomplish all of the objectives as ordered, you must meet the scouts within a certain period of time, and you must avoid being detected by the rebels holding the fort before you get inside. The route you take to get there, and what you do on the way, can influence both of these contingencies.

Meet the Scouts
The meeting point is on a cliff to the southwest of the fort. If your route takes you next to the fort before you reach them, you are likely to be detected by a rebel sentry. While you can successfully complete the quest in this event, you will not be able to complete all the objectives according to the plan. 

Accordingly, if you will fast travel to a location near the fort, you may wish to select a location to the west or southwest of the fort, such as the Nightgate Inn, Forsaken Cave, or Fort Dunstad. This will allow you to approach the meeting point without passing the fort. 




 
Once you approach the scouts at the meeting point, you'll find Hadvar again, commanding them. The number of men under his charge can vary from three to zero, depending on how many may have been taken by the hostile creatures which infest the area. 

Speak to Hadvar. His plan is for you to sneak into the prison section of the fort through a grate located outside the walls. You should then find and release the prisoners, after killing the rebels guarding them. Once you release the prisoners, you are to make your way with them to the courtyard and engage the main rebel forces, at which point Hadvar and his men will also join to assist. 

If you tell Hadvar that you are not much for sneaking, he will say that he has faith in you, but also that if you get discovered at any point, you should run out into the courtyard and start fighting, at which point he and his scouts will come running.

Hadvar will suggest waiting until nightfall before trying to sneak in. In reality, it's very easy to do this at any time.  

Your objective becomes to sneak in to the fort through the grate. However, you can successfully complete the quest no matter how you accomplish the fundamental objectives, which are releasing the prisoners and taking over the fort by killing all the Stormcloaks (in either order).    

Sneak Into the Fort
Stealthily enter the grate, to which your objective marker is pointing. If you are detected before entering the grate, the current objective will fail, but those of freeing the prisoners and taking the fort will become active, and you can still successfully complete the quest.

Despite Rikke's and Hadvar's emphasis on sneaking into the fort. It is actually not necessary to sneak at all because there are no sentries who can see in your direction unless you stray quite far out of your way to the north while en route to the grate. Head directly east toward the grate from Hadvar's location, jumping down the cliff and proceeding toward the quest marker. While you cannot be seen, it is possible for you to be heard as you approach the fort by a guard who is stationed just inside the wall. However, you must actually make an effort to generate enough noise to be detected. 

If you wish to practice your stealth skills anyway, you may wish to consider these detailed strategies:   



Free the Prisoners
Open the grate. Once inside, follow Hadvar's plan by killing the guards before releasing the prisoners: The prisoners are unarmed in their cells, and therefore won't be much help if released into a battle. Once the guards are dead, upon release from their cells, the liberated prisoners will equip themselves with armor and weapons from a chest on the level above.



After the three guards are dead, you can either practice some lockpicking to open the cells, or take the Fort Kastav Prison Key off any of the guards or the table on the level just above the cells. Once all of the prisoners are all released, your remaining objective is to take the fort by killing the rebels in the exterior courtyard. Make sure that all four prisoners are released: The related objective should clear and you will note in your journal that retaking the fort is your next task.  

Retake the Fort
The prisoners will equip themselves with armor and weapons and await your lead into battle. If you speak with them, however, you will have the option of ordering them to wait where they are.  

Lead them up and out into the courtyard and begin the attack. Hadvar and his men will join in the attack when the fighting starts. 

Unlike the battles at previous forts, no additional enemies will materialize during the battle, and the killed will remain where they fall for some time, giving you a chance to loot their bodies at your leisure. 

When all the rebels are dead, report back to Hadvar.

Report Back to Hadvar
Hadvar will inform you that he will remain to garrison the fort while you go to report the success. He will also lament that none of the prisoners you freed survived the battle if none of them survived. 

The quest will complete. If you have the underlying Reunification of Skyrim quest active, you will be directed to report back to General Tullius at Castle Dour in Solitude.

On speaking to him, the general will elevate you to the elite rank of Legate, and bestow upon you a piece of armor with the promotion. The quality of the armor may be underwhelming, especially if you are at a higher level although you can receive Dragonplate armor.

Notes
You will not receive this quest if Winterhold is given to the Imperials during Season Unending.
There may remain a Stormcloak on the roof of the Captain's Quarters who never becomes hostile during the battle, and does not have to be killed to complete the quest. If you go up to the roof after finishing the quest, but before you travel away from the area, the Stormcloak will warn you to leave since you are not welcome there, and may attack if you do not comply.

Bugs
 
The most reliable way to bypass this bug is to go to any indoor location and wait/rest for 30+ days.  This allows all location cells to refresh, and the next time you travel to the Winterhold Imperial Camp, Legate Rikke will offer the "Reporting for Duty" dialogue option.
Repeatedly asking General Tullius, "How is the war going?" seems to fix the issue, and Rikke will eventually present the option. You may have to ask him each time you complete the missions, or alternatively you could try attacking her until she retaliates, then sheath your weapon and open dialogue again; this will sometimes work.
 You can use the console command   to start the mission. If nothing else works, you may need to complete the entire Reunification of Skyrim quest via the console command  . You cannot use the console (setstage) to start the next appropriate quest.
 
Kill all the unnamed imperial soldiers that were prisoners. You should then be able to continue the quest by talking to Hadvar.
 
Simply tell Hadvar to follow you again, then proceed.

Quest Stages