Back when the game was still new, I wanted to advance the Civil War as much as possible for one side, then side with the enemy during Season Unending. I know that doesn't make much sense, but I wanted to see what happened. However, I was told at the time that you could only do Season Unending before the attack on Whiterun, which is also before you can actually take over holds in the civil war. Well, I was reading up on it just now and it seems that you can, in fact, obtain and complete the battle for Whiterun and then get Season Unending.

So my question is, how much of the civil war questline can I complete before Season Unending is no longer available?

http://www.uesp.net/wiki/Skyrim:Season_Unending


If you are playing Imperial, the Stormcloaks must still hold Eastmarch and at least one other hold.

If you are playing Stormcloak, the Imperials must still hold Haafingar and at least one other hold.

Ah. I'm not sure how I missed that. Either way, all of those numbers are just confusing me. I guess I would just advance the quest line for the Imperials up until the Stormcloaks only have Winterhold and Windhelm? Would I then be able to complete the civil war after the main quest without it glitching up on me?

According to the wiki, as long as either side controls at least two holds, you should be fine. One of them will always be the hold where the capital is, as those holds are the last to fall on either side. I can't remember which holds are second to last on each side but if you still have at least one hold to take before going after the capital hold then that should be as far as you can go.

To break it down, if you are playing Imperial: at the start of the game, the Stormcloaks control Eastmarch (Windhelm), the Rift, Dawnstar, and Winterhold. As long as they still control at least two of those, Season Unending should be triggered when you approach Baalgruuf about using Dragonsreach.