Its fair to say, like all conflicts, the civil war is a complex one and one which many people have differant motives for playing a part in. And, again like flowerbloom said, it makes Ulfric an even more sympathetic figure because all evidence suggests that he doesn’t even know the extent to which he is being used. Say what you want about the Thalmor, but their use of Ulfric in this regard has been brilliant. His every action is meant to further destabilize an already weakened Empire. Ulfric’s part in all of this becomes even more interesting when you realize that he is actually a sleeper agent of the Thalmor. The Empire demanded that he rescind the promise of Talos worship because, as flowerbloom said, a second Great War would be the result if an Imperial province was in violation of the White-Gold Concordat.
When the dust had settled and Jarl Igmund was safely perched on the throne of Markarth he discovered that his mouth had written a check that his backside couldn’t cash. Actually it was Igmund, son of the slain Jarl of Markarth, who promised the free worship of Talos to any Nord who helped him in re-taking the Reach.