Stormcloaks Or Empire (One Of The Three Certainties Of Life)

[Keltest]

Someone is arguing without actually bothering to learn the details of what he's arguing about.

The Thalmor detained Ulfric after the Markath incident, and was only released after his father died and he was the sole heir. For all we know, all of Ulfric's followers in Markath were killed in a Thalmor prison.

That someone being you, apparently, because Ulfric was detained by the Jarl of Markath and the Empire after the Incident, not the Thalmor.