The House of the Dragon season 3 episode 5 trailer teases a game-changing betrayal that you won't see coming — here's why it'll be so important to the HBO Max show's story

• HBO has released a mid-season trailer for House of the Dragon 3
• It teases the high fantasy show's next major battle in the Targaryen Civil War
• A game-changing betrayal could happen soon, too

The Dance of the Dragons is about to get even deadlier and more deceitful in House of the Dragon season 3.

Indeed, with its fourth episode officially marking the midpoint of the show's latest installment, HBO has released a foreboding new trailer that teases what's to come in the weeks ahead. Judging by the latest round of footage, we can expect another major battle to take place — in episode 5 or beyond — that'll reshape the entire Targaryen Civil War, too.

There's plenty to unpack from this new hype-inducing teaser — Rhaenyra's continual descent into madness and the return of Aemond Targaryen, whom we haven't seen since episode 2, being chief among the biggest reveals.

It's the HBO Max TV series' interpretation of the First Battle of Tumbleton, though, that takes center stage here. Indeed, we see Daemon Targaryen's forces converging on the market town that — at this moment in time, anyway — is still loyal to Rhaenyra and Daemon. However, with Ormund Hightower's forces occupying the strategic settlement's buildings and streets, a life-threatening fight for Tumbleton — and, by proxy, the Iron Throne itself — awaits in the Game of Thrones prequel's next chapter.

Why the First Battle of Tumbleton is such an important event in the Targaryen Civil War

It would be incredibly unfair of me to spoil everything that happens during the First Battle of Tumbleton, especially with the conflict potentially being the focus of next week's episode.

That said, there's a particularly vital incident that occurs— one that House of the Dragon has been sowing the (dragon)seeds for since its third season premiered — that's worth raising. The reason? Basically, it turns the tide of the Targaryen Civil War in favor of House Hightower, aka Team Green.

Full spoilers immediately follow for Fire and Blood, the book that House of the Dragon is based on. Turn back if you don't want this season's fifth chapter ruined before it airs on one of the world's best streaming services.

If you've read Fire and Blood, and/or know your Thrones lore, you'll know I'm referencing the moment known as the Two Betrayers.

During the First Battle of Tumbleton, Hugh Hammer and Ulf the White, both of whom are of Targaryen blood and swore their allegiance to Rhaenyra in season 2, defect to Team Green. As part of their betrayal, the pair use their dragons Vermithor and Silverwing to burn Tumbleton to the ground. Not only does Rhaenyra lose two of her dragon-riding allies, she also a key stronghold in a vital region of Westeros.

Fire and Blood doesn't contain an explanation as to why Hugh and Ulf turn their backs on Team Black and join the Hightowers' cause.

Admittedly, Rhaenyra hasn't helped her cause — after all, among other things, she refused Ulf's request to officially bear the Targaryen name when he was knighted, and she's been incredibly short-tempered and cold with Hugh since taking the throne. Nonetheless, with two less dragons on our side, things could be about to get even dicier for Rhaenyra as she struggles to retain her sanity and the wider support of the realm.

Anyway, HBO's adaptation has taken certain creative liberties with its source material and added narrative content to illustrate why characters make the choices they do. So, don't be surprised if, as long as the First Battle of Tumbleton occurs in season 3 episode 5, it includes some new material that, the above reasons notwithstanding, spells us why Hugh and Ulf symbolically stab Rhaenyra in the back.