All season long we’ve been teased that “War is Coming.” Now it’s almost here. On Game of Thrones, we’ve seen fights, executions, scheming, magic, sex, torture and romance. Next Sunday, the HBO hit that’s redefined fantasy television will stage its first large-scale war sequence. EW.com spoke to Thrones showrunners David Benioff and Dan Weiss about the making of the eagerly anticipated episode, “Blackwater,” and how the hour was itself a battle to get produced (and after the interview we have a new trailer for the episode).

The first part of this interview was conducted in HBO’s Los Angeles offices several months ago. The producers had just finished shooting season two. There’s some very minor logistical spoilers in terms of the raw battle components, but nothing that isn’t suggested in HBO’s preview.

EntertainmentWeekly: So how was shooting the Battle of the Blackwater?

Weiss: The Blackwater stuff was so much fun. I mean, it was miserable. Forty-two degrees and raining and mud up to your ankles.

Benioff: This whole story of Blackwater goes back to the first season because we were supposed to have that battle with Tyrion and we ended up not able to shoot it. And so we had him go down to friendly fire early. We always promised ourselves, we’re gonna have our major battle.

Weiss: We always wanted to do it and we didn’t know if we’d be able to pull it off. I mean, it’s a massive battle and it’s a naval battle and involves so much visual effects. And at the last minute due to a personal emergency the director had to drop out. So we were left without a director and about a week before.

Benioff: We were scrambling. We were like going over the list of who is available. And most of it was really terrifying. And then on that list Neil Marshall’s name pops out. He did Centurion and Dog Soldiers, movies where the guy’s doing an incredible amount of really intensive, impressive action on a thin budget. He had never seen [Thrones] before. We had to give him a crash course. But he’s such a fast learner and so enthusiastic and just fell in love with it and ended up being a great choice.

Weiss: He was a kid with the giant crayon box with the sharpener on the side. He got to play with all these amazing toys and built this amazing 80-foot high battle set out in the middle of this quarry, with fully functional castle walls and gates and everything. He was throwing stuff in instead of taking stuff out.

And I’m assuming you set it at night so you don’t have to do full CGI backgrounds of every shot?

Weiss: It was partly budgetary. But there are certain elements of the battle we always thought will look so much more intense at night.

Benioff: Flaming arrows at night look gorgeous.

Elements of this kind of battle have been done before, particularly Helm’s Deep sequence in LOTR. Can you talk about how you went about dramatizing Blackwater in a fresh way?

Weiss: On the resources we have, you’re never gonna be able to compete with that level of spectacle. It really has to become more about pulling into the characters and making it more about their personal experience of this event rather than giving us the giant bird’s eye view.

Benioff: One great advantage we have over the movies is that when one of our characters wades into battle, we’ve spent almost 19 hours with these characters. You know them so well and hopefully you’re worried for them. And some of them are gonna die. There is a way of shooting a battle where you see an army of a hundred thousand attacking an army of two hundred thousand. There’s also the ground’s eye view where you’re an infantryman and you’re running out there with an axe or a sword or something, you’re not seeing the grand scale of it. You’re just kind of seeing what’s directly in front of you. And that can be a really visceral way of shooting a battle.

Weiss: Any time you read any military account of a soldier’s experience of battle, whether it was in ancient Rome or all the way up to Vietnam and beyond, it’s never, “Then this flank moved over here.” It’s always, “This chaotic, cluster f–k and I didn’t know which way I was going and half the time I wasn’t sure if I was shooting at my own guys.” It’s that fog of war experience that you actually can replicate without showing the giant Helm’s Deep kind of battle.

Can you give a sense of what you had to go through to shoot that?

Benioff: I think pretty much a month straight of night shoots, which is just tough for anybody unless you’re a vampire. It’s Belfast nights, which means it’s cold and it’s usually wet. There was an incredible amount of mud. It’s tough for the crew, but then when you actually see it on screen and see how good it looks, you see the way the weather affects people. You see the wind blowing their hair and the rain coming down. None of that’s faked.

Weiss: The weariness and the bleariness that you see on the people on screen feels real because it is real. We needed an extra sort of stipend to do it ’cause there was no way to fit it into the box that most episodes fit into.

Benioff: We went down on bended knee [to HBO]: “Just this once. Please.” We were genuinely nervous about it for the whole time until we finally wrapped it. The impressive thing about the conversation where we went in asking for more money, a considerable sum, in order to shoot the Blackwater battle — we didn’t get everything we wanted — but [executives did not ask]: “Will this attract more viewers? Is this something that’s gonna pump ratings?” It’s all about why this story needs this big battle. “You guys were able to do the first season successfully without major, big scale battles, [so] why does this one need to have one?” And so it was really a long conversation about how the second season all builds towards Blackwater. You know it’s coming from quite a ways off and for us to all that build up and then have someone running in and saying, “The ships are in the bay!” Certainly other shows have gotten away with it. But it felt like it was gonna be cheap if we did that.

Now fast forward to last week. The producers have finished all the post-production work on “Blackwater.” These questions were answered by email.

Did “Blackwater” meet your expectations?

Benioff: The episode has dramatically exceeded our expectations, and much of the credit for that goes to our superhuman [visual effects] team, lead by Steve Kullback and Rainer Gombos. When you look at the shadow demon Melisandre births, or the detailing on the dragons, or the beauty of Pyke, you realize you’re dealing with talents that could someday win an Oscar. “Blackwater” has far more VFX shots than any other episode we’ve done. We try to avoid excessive VFX on the show, but with “Blackwater” there was no alternative. Steve and Rainer look over a large team of tech wizards and what they’ve accomplished is, in our completely unbiased opinion, some of the best effects work in television history.

Weiss: And it’s not all visual. A big part of any battle scene is sound, and we’re lucky to have an amazing team. Ramin Djawadi, our composer, is equally adept at scoring a quiet, mournful scene or an explosive battle. And for this episode, we gave him an added challenge, the results of which people will hear in the episode.

Benioff: Then we have the sound designers, who have been working seven days a week, 16-hour days on this episode. It’s a monster episode, we all knew that going in, but foreknowledge doesn’t diminish the workload. Peter Brown, our sound designer, is our hero because he finally came up with the ice-cracking chatter we had in our heads when we imagined the White Walkers speaking Skroth. For “Blackwater,” he had to orchestrate a major naval battle and a land battle. And he had to come up with something very big and very loud, which would be a spoiler to explain but book readers will understand. Once Ramin composes his cues and Peter comes up with a sound design, we have the masterful Onnalee Blank and Matt Waters putting it all together on the mixing stage. “Blackwater” is essentially a short feature film, so their ability to get the job done on a TV schedule is astounding.

Weiss: And our colorist Joe Finley, who labors over each shot of Neil’s and Sam’s like a painting. And holding this whole team together is our post producer Greg Spence, who is a miracle. He works unfathomable hours, keeps 10,000 balls in the air at once and never drops one of them. Managing and coordinating the post-production workflow was a unique challenge here, and his perfectionism never flagged – not for this episode, and not for the whole season.

Going from page to shooting to editing, has anything significant changed along the way?

Benioff: Yes. First of all, we almost had no battle at all. For budgetary reasons we came very, very close to having all the action take place off-screen, the way plays have handled battle scenes for a few thousand years. The idea was [MINOR SPOILER ALERT] that we’d set most of the episode in Maegor’s Holdfast. Cersei and Sansa would be cooped up in there with the other noblewomen and children, hearing occasional reports from the battlements.

Given how good Lena and Sophie are, we could probably have made a decent episode, but we didn’t want to do it that way. Last year we had to cut a battle we wanted to shoot, and the Battle of Blackwater Bay is far more important. To our minds, the entire season builds to this clash, and if we didn’t see any of it, we were undercutting the story and short-changing the audience.

As we’ve mentioned before, we went pleading to HBO for more money. We made our case why we needed the battle and they obliged. That allowed us to do a battle. It did not allow us to do the battle from A Clash of Kings. It would be difficult for a $200 million feature to do justice to the battle from the book. We didn’t have a chance; there just wasn’t enough time on the schedule or money in the budget (even after our Blackwater bonus).

There was a good deal of pressure to turn Blackwater into a land battle. The Battle of the Blackwater Banks, I guess. And we understood the technical reasons why that would help our cause: land battles are much easier to shoot than naval battles.

Weiss: But we’ve seen so many pitched battles in epic fantasies, and relatively few naval battles (probably because most people making epic fantasies are smarter than we are and know to avoid them). And the split between army power and navy power is central to George’s story and the whole dynamic between Stannis and Renly (and indirectly central to the Tyrion storyline as well). Going with the exclusively land battle route would ultimately have meant rewriting the whole season.

So we had to perform triage on the battle, determine what we could save and what had to go by the wayside. Quite a bit had to go, including some stuff we absolutely hated to lose. But it was really about keeping the heart of it intact, preserving the core elements that would give the episode the impact we need. In our unbiased opinion, we think that we – the collective ‘we,’ the team of hundreds and hundreds of people who worked like dogs on this thing into the wee hours of many, many nights – we think that we created an intense, dramatic battle.

Game of Thrones author George R.R. Martin wrote the episode. Can you talk about his contribution to the episode and to the season in general?

Weiss: Yes, when we came to George with the harsh production realities, he was very helpful in helping us find our way to a lean – but still incredibly mean – Blackwater Bay. He contributes to every season in numerous ways. Such as… well, inventing all the characters and main storylines, for one.

Benioff: George created the world that we’ve lived in for the past six and a half years, so the word “contribution” doesn’t encompass the scale of what he’s provided for the series. We were at the Paint Hall with him during season one, showing him one of the sets, and he said, “So this is where they’ll shoot the scene from my episode?” And we looked at each other and one of us said, “George, they’re all your episodes.” The characters sprang from his brain, so did all the major storylines, so did all the prominent characters. We wanted to give him “Blackwater” to write because no one writes better large-scale battles than George. Ultimately we had to sacrifice some of that scale. There are some wonderful moments from the script (and book) that we wish we could have afforded. But when you’re delivering ten hours of epic fantasy in less time than a studio feature delivers two hours, it just isn’t possible to shoot everything you want. It always comes back to horses or Stonehenge.

Check out EW.com’s recap of the Sunday’s episode of Game of Thrones here.