Warning: You're charging straight into spoilers like a Dothraki horde.
This post contains a whole bunch of spoilers for Game of Thrones Season 8 Episode 3, The Long Night--you've been warned!
The Battle of Winterfell during the latest episode of Game of Thrones Season 8, "The Long Night," was the biggest the show has ever undertaken, and in a lot of ways, one of the most complex. The final showdown between the Night King and the forces of the living brought together tons of characters, and much of the fighting devolved into chaos. After watching the Battle of Winterfell, though, a lot of viewers have wondered what exactly Jon Snow and his comrades were thinking--because it seemed like they made mistake after mistake, from the very first.
The battle seemed like a disaster from the start, and whatever game plan the heroes had for fighting the Night King didn't make a ton of sense. A lot of people died seemingly needlessly (sorry, all the Dothraki), and their most powerful weapons, like Daenerys's dragons and the castle's huge trebuchets, weren't much of a factor.
While no plan survives contact with the enemy--as the cliché goes--Jon did have one. In the previous episode, A Knight of the Seven Kingdoms, he gave a brief overview of what to expect during the battle. Essentially, it came down to a piece of information Jon and his allies discovered during Season 7 when they went north of the Wall to capture a wight. There, they killed a White Walker; when they did, all the wights it had created died with it. Jon extrapolated that bringing down the Night King would destroy the entire army and all the other White Walkers, so the battle plan at Winterfell was all about getting to the Night King. Here's how it was supposed to work:
During the war council, Jon laid out that the key was to take down the Night King, but the worry was that if killing him was the key to victory, he wouldn't expose himself, as Jaime Lannister pointed out. But Bran said that the chance for the Night King to get to and kill Bran would draw him into the open. Let's ignore the fact that any wight could easily eliminate Bran, rather than the Night King himself, and assume there's a reason the Night King had to do it himself.
This shifts the entire battle plan for the living. Trying to defeat the Night King's army in a straight fight is expected to be impossible--there are too many wights, they don't feel pain or tire, and their numbers can be bolstered with every single soldier they kill. Instead, the heroes are trying to last as long as they can against the dead, while leaving Bran in the godswood with a small detachment, made up of Theon and the Ironborn, protecting him. The idea is to use Bran as bait for the Night King, with Daenerys and Jon and their dragons waiting to ambush him when he shows himself.
The combined armies of the North, the Unsullied, the Dothraki, and the Freefolk appear to be too many people to leave inside the walls of Winterfell, which is why so many troops are arrayed outside the walls. They're hoping to do as much damage as they can to the army with siege weapons, cavalry, and foot soldiers. But the plan has Daenerys and Jon, and the dragons Drogon and Rhaegal, specifically sitting out most of the fight. The dragons are great at destroying ground troops, especially wights, but the worry is that if the Night King sees the dragons, he'll stay back out of the fight. The only chance the forces of the living have is to draw him into the open as quickly as possible, and that means holding the dragons in reserve to fight the Night King himself.
Then there's the trench, a line dug around Winterfell that's filled with flammable pitch and wooden barricades outfitted with dragonglass spikes. When the army of wights becomes too much, the Unsullied and the rest of Winterfell's forces are meant to fall back behind the trench, drawing the wights into it. On the castle walls, Davos will use torches to signal Daenerys, who will light the trench with Drogon's dragonfire. That will create a huge barrier that'll kill a bunch of wights and leave a bunch more unable to press the attack--at least for a while.
That's not how it goes down, though. The Dothraki charge the dead (for some reason, since that seems like a really bad use of them), but are wiped out almost immediately. It's unclear if this was part of the plan--in which case, what the hell--or if the eager and confident Dothraki simply jumped the gun. Either way, seeing her people in trouble, Daenerys refuses to stay back, and instead hops onto Drogon and joins the fight. She and Jon strafe the army of the dead with dragons, killing a bunch and helping the fighters on the ground weather the attack, but it messes up the plan to try to hide the dragons to draw the Night King to Bran.
And then the snowstorm blows in, presumably summoned by the Night King and his icy magic. The storm blinds Daenerys, Jon, the dragons, and the fighters on the ground, giving the wights a lot more ability to close in on them. The Unsullied are then meant to guard the retreat back behind the trench for a new line of defense on the castle walls, but the storm means Davos's signal to Daenerys doesn't work, and she can't light the trench. Luckily, Melisandre is there to handle the job with magic.
Jon's battle plan seemingly doesn't account for one big problem: The Night King's dragon. Winterfell has nothing in place to deal with a flying undead dragon, and when the Night King and the wight Viserion show up, they mess things up pretty good. Still, Jon and Daenerys are running their part of the plan by tangling with the Night King and Viserion--if they manage to kill him, the game is won, so it's much more important to fight him than to help the soldiers on the ground.
The portion of the plan to lure the Night King to Bran does work, in the end, but not as Jon and Daenerys envisioned it. Jon's plan was to get to the godswood to either blast the Night King with dragonfire or to take the King down with Longclaw, Jon's Valyrian steel sword. Fighting in the air with the dragons means both Jon and Daenerys are both stranded away from the godswood and never make it to the final fight; what's more, Daenerys and Drogon manage to blast the Night King with flame, but it doesn't work.
Luckily, the Ironborn hold back the wights long enough for the Night King to come out into the open. And the Night King didn't account for Arya, who is probably the best and deadliest fighter in the Seven Kingdoms by this point. Small as she is, she manages to use all her training to sneak in close to the Night King, fake him out, and stab him with her Valyrian steel dagger.
So that was the plan: Let the forces of the living fight and die for as long as they can manage, hoping the Night King will show up and try to go after Bran, so Daenerys and Jon can dragon or Valyrian steel him to death. You can argue that many of their forces and assets were arrayed improperly and deployed illogically, but the episode itself simply wasn't concerned with the logistics of how cavalry should be used or where catapults ought to be placed--and neither were the many viewers who enjoyed watching it.
In the end, the dragons didn't turn out to be deadly to the Night King at all, and a lot of people died fighting the army of the dead without air support from Dany and Jon. But the Night King's overconfidence and obsession with Bran meant he still fell into the trap, and thankfully, Arya Stark was there to seal the deal at the last second when Dany and Jon failed to appear.
Need more Game of Thrones? Check out our review of Season 8 Episode 3, a rundown of who has died this season, a list of the Easter eggs and references you might have missed in The Long Night and some theories for the rest of Season 8. We can also catch you up on what happened to Jon Snow's dragon, Rhaegal, and his direwolf, Ghost--who both made it out of Episode 3. Finally, we explain why it's really dumb to say Arya Stark is a Mary Sue.