Picking a side in Skyrim’s Civil War has always been a no-brainer for me: the Stormcloaks are a racist lot with so much deep-seated hatred towards immigrants that I can’t stomach being near them, let alone taking up arms to fight alongside them. Yet, the Imperials are under the long winding elvish thumb of a race with a superiority complex that rivals even Ulfric’s, but at least they’re biding their time to fight back. The reality, however, is that this whole Civil War is pointless as all it does is help the Thalmor. We’re lulled into thinking our choice means something, but take a step back and think about what would really happen between Skyrim and The Elder Scrolls 6.
It’s an egg that Bethesda is going to have to crack when it comes to the long-awaited sequel: who won the Civil War? There’s always the option of staying vague about events, but something of that caliber will no doubt be a hot topic of conversation across Tamriel - just look at Hammerfell’s own stand. The issue is that Bethesda has never truly picked a singular choice-based option as the canon in their world. Instead, it often finds long-winded convoluted ways to make it all fit in. For instance, Morrowind made every single ending from Daggerfall the ’true’ ending since they all happened simultaneously due to The Warp in the West.
Then, Morrowind’s protagonist was sent to Akavir, while Oblivion’s became Sheogorath. Bethesda finds neat little ways to avoid recurring player characters and set-in-stone choices actually having an impact on the world. This is to let those choices be self-contained and meaningful within their own games, rather than sullying them in sequels. Skyrim’s own sequel can continue that trend with one option that makes perfect sense: who wins is null and void. The Thalmor let the civil war run rampant across the meadows and mountains of Skyrim so that, slowly but surely, the inhabitants would become meek and downtrodden. This is due to inevitable rations, diseases from the mounting corpses, and the instability that stems from so many crowns being passed around with Jarl after Jarl being replaced. What you get is deep-seated hostility breeding among the country even in the wake of the war’s end - the Battle-Born and Gray-Manes of Skyrim.
At any time, the Thalmor could have swooped in to offer aid in stomping out Ulfric’s incursion, standing side-by-side with the Imperials, but why bother? What the civil war does is blatantly obvious. It weakens the Imperials who are biding their time to recuperate and regain strength so that they may take up arms in a second war against the Thalmor. It also weakens Skyrim, a potentially pivotal state in the overthrowing of the Thalmor overlords should the Nords stand side-by-side with the Imperials of their own volition. I posit this: the Thalmor didn’t outlaw the worship of Talos due to their own principles, but rather because they knew the seed it would sow, that of hostility to those occupying the land which wasn’t them directly but rather their proxy, the Imperials. Their two enemies pitted against one another.
With that, the sequel can have one canonical path moving forward. The Thalmor, in the wake of the Skyrim civil war, descend to occupy the country directly. If the Imperials won in your prior game, then the Thalmor have arrived to take control of Skyrim, ripping the reigns from a weakened old general and his ill-equipped army. The civil war failed, and surely they won’t try again - they can’t, they’re too weak now. The Thalmor didn’t have to lift a finger in stopping any uprisings, they let their enemy handle it for them, weakening them to boot. However, if you helped to aid and abet the Stormcloaks, then the Thalmor began to cut important trade routes following their victory, limiting supplies, food, medicine, and wares. Weakened by both a civil war and a lack of incoming trade, the people begin to sour against the Stormcloaks, and the Thalmor arrive to take out Ulfric and his cronies with ease as their armies are depleted from the civil war, with their soldiers malnourished and weakened.
Either way, the Thalmor can take Skyrim with little tribulation. No matter the side you ultimately ended up picking in your playthrough, or the side that you support regardless of who you actually pick when playing, the Thalmor win. It’s an unfortunate way of looking at it, given how utterly bleak it makes the entire affair but it’s what makes the most sense. Why else would the Thalmor leave the Imperials to their own devices in handling an uprising in an important state? They know that no matter who wins, taking the country by force and occupying it with their own soldiers on the streets, usurping the Jarls, will be easier should the Nords tear themselves down first. What’s more, Ulfric is a Thalmor asset, even if unwilling, and has been tortured and blackmailed by them. It’s clear that he’s a pawn in their game even if he doesn’t realize it, and what does he go on to do following his release? He incites a civil war. It’s what the Thalmor wanted because it’s what benefits them most of all.