SPOILER ALERT: This article contains spoilers for the Season 3 premiere of “House of the Dragon,” now streaming on HBO Max.

During early discussions about how they would pull off the much-anticipated Battle of the Gullet sequence that opens “House of the Dragon” Season 3, director Loni Peristere (who previously directed the “Red Sowing” episode of Season 2, and calls himself the biggest “fanboy” of George R.R. Martin’s books) recalls telling his director of photographer, P.J. Dillon, one important thing: “We need to go back to what epic means for battles at sea.”

Peristere got his core creative team’s juices flowing after seeing the historical Battle of Trafalgar painting, depicting Lord Nelson coming out a “heinous” battle surrounded by dead bodies in water, and catching a London screening of Peter Weir’s 2003 epic “Master and Commander,” which ultimately informed the crew’s approach to capturing the “living, breathing life of a ship.”

The Battle of the Gullet (originally cut from Season 2 due to budget constraints) is finally here, showcasing the epic naval battle between the Blacks, Rhaenyra’s (Emma D’Arcy) forces, and the Greens, the King’s Landing loyalists under King Aegon II (Tom Glynn-Carney). The sequence required full-scale versions of Corlys’ (Steve Trussaint) and Lohar’s (Abigail Thorn) ships to be built and usable on both a dry tank and wet tank, thousands of gallons of water and extras and, naturally, numerous CGI dragon fights requiring mechanical bucks.

With the help of naval adviser Craig Lambert, the “House of the Dragon” crew pulled references from how real vessels work to construct both ships — the Queen Who Never Was and Bitchfist — efforts largely led by production designer Jim Clay and line producer Kevin De La Noy.

“There was a really big desire from all of us, despite being surrounded by blue screens, to put it all on the deck. Even though we’ve got land, sea and air, we wanted everything that was on the deck to be legitimate and real and present,” Peristere says. “So when you’re with [the dragon] Shrykos and she calls the order, ‘Take the ship!’ it’s like we are with her, and we do that uninterrupted cut [with a] little seamless stitch that you don’t even see.”

That mentality also extended to Peristere’s work with the actors: “We rehearsed all of this work with real naval people that were on those decks so that everybody in the background is doing the right thing.”

The episode had to be meticulously planned with everyone “on point,” Peristere says, including crew members directing the movement of the water cannons. He even created a 186-page Wikipedia-style document with information for every department head, based on levels of blood and wind needed for certain moments.

“Even though we have a decent budget, we’re not a $300 million motion picture. So everything we had to do had to happen on the day. We’re not Marvel,” he says. “The next day, if you didn’t get the shot, that didn’t work because we had a very tight schedule.”

Beyond the episode’s gigantic set pieces, Peristere recognized the need to center the human drama and characters — especially with the two-year gap between Seasons 2 and 3: “We taped out the deck of the vessels on the inside of a stage, and we started, ‘Let’s rehearse with just the cast. Let’s talk about drama.'”

One of the most shocking moments of the episode comes when Jace (Harry Collett), Rhaenyra’s eldest son, dies after being struck by arrows from a rival ship in water (Collett spoke with Variety about why filming the scene was so difficult.) Collett was intentional about how he played Jace’s final moments in the water, along with the death of his dragon, Vermax.

“Even when the arrow comes, Jace is like, ‘I’m a god, I’m a dragon rider. And when I pop up and I take that gasp of breath, even though I’ve lost my dragon and I’m heartbroken, I never once think I’m going to die. Baela is going to pick me up,'” Peristere says. “Harry really leaned into it, and God bless him, because we put him through the wringer.”

Tracking the episode from it’s start on a foggy morning gives the viewers a full scope of the day and “feeling that sun change,” as the death count settles in: “When we get to the finale, when all is lost, we wanted that feeling of separation. Driftmark is gone, the ship is lost, there’s bodies in the world, and there’s nothing we can do about it,” Peristere says. “It’s just hell on Earth. When you see those last two frames in the episode, it’s like, ‘Wow, we just had the biggest epic battle ever. It sucks! It feels terrible!'”

The Battle of the Gullet sets this season into motion with literal fire. Rhaenyra will not only have to contend with the death of yet another child, but also that same child’s decision to betray her and lock her away in a room.

“As Rhaenyra, who’s being pushed aside, can’t be king, can’t sit on the Iron Throne and even with her own family within her own court, they’re locked in — we literally watch Emma D’Arcy become queen, king in that moment,” Peristere says. “And then she brings that knife down, and that’s just the course. That knife is going to go into the whole hierarchy and we can feel that coming. It leads us right into Episode 2, which Claire [Kilner’s] brilliantly directed, and honestly, the start of what canonically is going to become a bit of madness.”