#ysmir

However, in the lore, this is established:

Talos is a relatively new god that has usurped the Nordic Ysmir by fusing the legend of Ysmir Wulfharth of Atmora together with Hjalti Early-Beard/Tiber Septim and his right hand Zurin Arctus, via a Dragon Break named the Warp in the West created by Tiber Septim whose propaganda made him Talos of Atmora even though no one has come to Tamriel from Atmora in literal eras because it is now a frozen wasteland. The whole Nordic worship of Talos itself is an Imperialist trick to ensure the Imperialization of the Nords (yes, Talos is a god and has the powers and whatnot, but this still Imperialized Skyrim faster by equating Hjalti with Ysmir).

Ulfric sparks two rebellions by taking the religious freedoms and ancestral lands from the Reachmen while loudly complaining that he cannot worship Talos like a TrueNordTM in his ancestral homeland (that, btw, he still rules as Jarl, oh and the whole Talos of Atmora bit should make Atmora more of his ancestral land than any part of Skyrim, much less south-western Skyrim!). This leaves the Reachmen devastated, divided and in serfdom to the Nords (and thus so much more worse off than Nords after the Talos ban). The Stormcloak side also complains a lot about lack of faith/loyalty among Imperials, and at this point Ulfric is sworn to the Empire and he breaks faith with it.

He is also sworn to his High King, that he murders with his Voice before running away (instead of staying and taking the throne like a TrueNordTM would have done). We learn that violently using the Voice unless you are Dragonborn is against another ancient Nord philosophy/religion “The Way of the Voice” as taught by the Greybeards to Ulfric when they taught him to Shout, and the Way of the Voice is an ancient Nord philosophy that he has then broken for his own ends.

We also learn how he mistreats/neglects the citizens of his own Hold (Dunmer, Argonians, women, orphans...), which is a complaint he raises against the Empire’s treatment of him and his Stormcloaks.

And finally, we learn that the Thalmor actually likes the Stormcloak Rebellion and that up until the Markarth Incident, Ulfric was working with them (now he’s “unknowingly” working for their interests though any dying brain cell would figure out that he’s supporting the Dominion with his actions [and I am under the belief that he sparked the Forsworn Rebellion for them, and to the Thalmor the Stormcloak Rebellion was an unexpected bonus, akin to Naarifin’s conquest of Cyrodiil], and also, why doesn’t he question all those convenient supplies and info that the Thalmor keeps dropping in his lap? Not that it stopped Tullius from defeating him in a few months in Ulfric’s own Hold...).

And then we have Froki blatantly telling us how Imperialized the current Nords are in their religion (though badly, if he was to be only rep for the old gods, he, and his questline, should have been much more developed, and he should have not been the only follower of the old ways).

Basically, the heart of the Stormcloak Rebellion, and the Civil War, is Hypocrisy and the Glorification of Ulfric Stormcloak.

That’s why it has to be Talos and cannot be Ysmir, Sai or Shor. The God of the Empire has to be worshiped by the Stormcloaks because he is the God of the Empire they rebel against (and thus their true loyalties when it comes to Talos worship are in question). He has to be the Breton impostor usurping a Nordic legendary hero-king-god to force everyone into his Empire, because it mirrors Ulfric’s duplicity and self-serving actions.

If it was any ancient Nordic god, it would have been about what Ulfric claimed it to be: The defense of Nordic religion and culture, and by extension, the Nordic peoples.

It is not. Just like how the current uber-Nord Talos of Atmora worship is all about the deification of Tiber Septim, a Breton from Alcaire, the Stormcloak Rebellion is all about the Cult of Personality of Ulfric Stormcloak.