Here guys, three options if you play on PC (not limited, just three that are supposed to work). My heartfelt thanks for figuring it out go to; noxaeXXX (YouTube user), The Elder Scroll Wiki, and the Unofficial Elder Scrolls Pages. The tow latter sites are great for tips and learning console commands.
1. Become a werewolf, transform in the imperial camp then run away, wait a few hours, then come back. Option should be there.
2. Become a LV4 vampire, summon a permanent follower (like Lucien Lachance). Become invisible and fast travel to the imperial camp. Let the imperials kill the follower then dip from the scene. Cure vampire and smile as the legate gives you the next quest.
3. If you're an Imperial, attack the Legate, then use Voice of the Emperor to calm her and ask away. If you're not an Imperial here's the console code to get Voice of the Emperor: player.addspell 000e40ca
Try these and if they don't work then don't lose hope! I know how bad it feels not to subdue Ulfric Stormcloak

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I'm sure we will figure out something that definitely works; THERE'S NOOOOOO DOUBT ABOUDIT!!!
