This month, June 2015, marks the bicentenary of the Battle of Waterloo, the decisive European conflict of 1815 in which the French Emperor Napoleon and his army were defeated by British and Prussian forces.

It can be no coincidence that BBC Television has chosen this season of commemoration to air Jonathan Strange and Mr Norrell, a dark fantasy in which two rival magicians of the 19th century direct their otherworldly powers to aid the war effort at Waterloo. Adapted by Peter Harness from the award-winning novel by Susanna Clarke, the seven-episode show is directed by Toby Haynes, and features around 1,000 visual effects shots created by a team of 50 artists at Soho-based Milk VFX.

“The show’s producer, Nick Hirschkorn, is a long-standing client of ours. About four years ago he told me he’d just acquired the rights to Jonathan Strange and Mr Norrell,” recalled Milk CEO Will Cohen. “I got very excited – I’d read the book when it first came out, and loved it. The show went into preproduction in April 2013, at which point we sat down with the first scripts, and had initial meetings with the production designer [David Roger] and the director of photography [Stephan Pehrsson] to discuss how to bring it alive.”

The Battle of Waterloo

Throughout the series, the magical powers of Jonathan Strange (Bertie Carvel) and Mr Norrell (Eddie Marsan) are made manifest through a number of supernatural set-pieces. One of the most spectacular of these occurs at the beginning of episode five, when Napoleon’s army attacks the British and allied forces at Château d’Hougoumont in Belgium – a key moment in the Battle of Waterloo.

During the sixty-second opening shot, the camera swoops over a smoke-covered battlefield filled with tens of thousands of warring soldiers and resounding with cannon-fire, before finally descending into the fortified garrison of Hougoumont, where Jonathan Strange is using his magic to help repel the enemy hordes.

“Instead of just seeing twenty extras in the scene, with the main battle happening off-camera – which is a very ‘television’ conceit – we wanted to get the full horror of the fighting,” remarked Cohen. “We’ve done similar scale shots for films, like Insurgent, so to me it represents a crossover to what you can do with high-end television in 2015. I’m really proud that the producer and director and execs backed up doing it.”

Watch a video breakdown of the Battle of Waterloo sequence:

Inspired by the battle scenes in Sergei Bondarchuk’s 1970 film Napoleon, the Milk team set about crafting the Waterloo sequence. “We worked out that in Napoleon there were about 40,000 extras,” commented visual effects supervisor Jean-Claude Deguara. “That film was also a great point of reference for us in terms of terrain and textures.”

To re-create the garrison at Hougoumont, a set was constructed at an airport location in Canada. The final frames of the grand opening shot were photographed as a crane move, with the camera descending from high level down into the set. Deguara and his team incorporated this live-action into the latter half of their shot, digitally replacing the airport surroundings with the appropriate terrain. The front end of the shot was fully digital.

For the most part, the terrain was historically accurate, based on both documents from the period and data gleaned from Google Maps. Further research served up facts and figures about how the troops were deployed on the day. While the environment and troop movements were reproduced as accurately as possible, artistic and technical considerations made necessary the occasional bit of historical revisionism. “We had to cheat it slightly to get everything in,” Deguara confessed.

Editorial and budgetary pressures meant that a shot as ambitious as the Waterloo flypast was constantly under threat of being trimmed – or even cut altogether. “We knew that this shot could potentially be chopped at any point,” remarked Deguara. “So we started off at a very basic previs level – the armies were just blue squares and red squares. We began with the movement of the camera, then gradually built it up, step by step. With a TV budget, you have to be so regimented in how you do it.”

CG supervisor Nicolas Hernandez added: “On a feature film, you can create an asset straight away that will be photorealistic for a full-screen close-up. On this show, we had to put in more time towards the end to get the assets looking nice.”

Trumping Bondarchuk, the Milk team populated their digital battlefield with no less than 50,000 soldiers. During production, performers and extras were photoscanned wearing period costume, with the resulting data being used to create multiple types of CG double, ranging from Napoleonic grunt to Regency officer.

To control these huge numbers of digital extras, Milk turned to Golaem Crowd, their crowd management tool of choice, which they had first used on Brett Ratner’s 2014 feature Hercules. “We had soldiers, captains, all with different guns, different uniforms, different props,” said Hernandez. “They were all procedurally managed by Golaem.”

Similar attention to detail was used when re-creating the firepower of the digital troops. “Every cannon had five soldiers around it, which was historically correct,” observed Deguara.

Simulation systems permitted each cannon to “fire” automatically. “The simulation worked out the projection of the cannonball, and where it would hit the ground,” explained Hernandez. “We imported it into Maya, where we used a library of explosions that triggered procedurally. The first version we did of the shot looked like a Michael Bay film! We had 25,000 explosions, and the whole screen was covered in smoke!”

Ultimately, the choreography of the cannon-fire – together with the rest of the action in the shot – was determined through a number of meetings with the director. “It was all about Toby’s subjective taste,” Cohen commented. “That included questions about whether the camera should get interfered with by the explosions and cannon fire, and at what point in the shot that should happen.”

The opening Battle of Waterloo shot took around three months to complete. During the refining process, the shot proved too complex for one person alone to check. “We had four people watching it back in dailies,” revealed Deguara. “They each took a quadrant of the screen. Each time we’d notice little mistakes and glitches – like a soldier who’s running through a tree – and we’d go back and fix them. We could still be working on that shot today!”

Magic at Hougoumont

Once the camera has finished its sweep of the battlefield, the action continues inside the Hougoumont garrison. As the French soldiers attack, Jonathan Strange uses his magical powers to help counter the onslaught. First, he brings to life the vines which ramble over the garrison’s fortified walls. Snake-like, one of the vines plucks an enemy soldier from the ground and flings him to his doom.

To achieve the effect, a stuntman was photographed on location, suspended from a wire rig. Hero vines, modelled and animated in Autodesk Maya, were tracked to his body. Just before the throw, the live-action performer was replaced by a digital counterpart.

In a classic piece of movie misdirection, the transition from stuntman to digi-double was concealed by the body of another soldier moving briefly in front of the camera. “You see the top part of the vine gearing up for the throw, then as soon as the other soldier wipes across the frame, we’re into our digi-double getting flung out of the way,” explained Deguara. “Actually, that was a reference to an episode of The Simpsons, when Bart and Homer are trying to trap a rabbit! It’s a comedy moment that we tried to slip in there.”

When the building behind him catches fire, Strange summons a giant waterspout from a well and uses it to extinguish the flames. “We had big fire hydrants and hoses there on the day,” recalled Deguara, “and we had real water pitching down over the doorway – interactive elements for when the soldiers run out. We did the shot with two camera moves, which we joined together. Our digital waterspout comes out of the well, then splits into five sections to put out the fire.”

The main body of the waterspout was procedurally generated in Houdini, with extra detail built up using liquid flip and white water simulations, plus layers of mist. Additional procedural tweaks were used subsequently to allow artists to choreograph the animation of the liquid. The central column was rendered in Maya using Arnold, while Mantra handled the more finely detailed effects in Houdini.

As the French soldiers press home their attack, the resulting hand-to-hand combat was enacted by actors and stunt performers. Weapon strikes were enhanced by Milk, using a combination of practical and CG effects to increase the blood quotient. “We got them to send costumes over,” stated Cohen. “We would put a costume on a dummy, and cut it as if it had been hit by an axe. Then we would photograph that and comp it into the shot.”

Towards the end of the sequence, Jonathan Strange finds himself at the mercy of a French soldier. Staring death in the face, he causes a giant facsimile of his own hand to rise up from the ground and uses it to crush his attacker to death. By the time the live-action for the scene was shot, however, the Hougoumont set had become a quagmire, causing Milk to reconsider their initial design for the effect.

“We originally thought the hand would be made of dry, crumpled mud,” Deguara commented. “When we got the plate back the place looked like a swamp, so we had to re-evaluate it. We turned the hand into something more muddy and slimy. I think it worked in our favour, that fluid look.”

The geometry of the CG hand was deformed to give it a liquid appearance, with viscous fluid particles being emitted from the more distorted areas to produced falling chunks and streams of mud. Additional displacements and variations in colour, applied at render time, added the interactive effects of the rain which falls throughout the scene.

As with the vine sequence, the actor playing the doomed French soldier was held aloft using a wire rig. “We couldn’t afford a digi-double for that shot,” noted Hernandez. “The hand is animated to the guy on a wire – it was a bit tricky, but we did get it to work in the end.”

Equally tricky was making the soldier’s death gruesome, yet without upsetting squeamish viewers. “There were a lot of taste decisions to be made,” Cohen remarked. “Originally, as Jonathan Strange squeezes the life out of the soldier, his head was going to pop off. But even though it’s after the nine o’clock watershed, there’s still a line you can’t cross!”

The Waterloo scenes are augmented by a number of environment extensions and matte paintings, including the final shot in which the camera cranes up to reveal a wide shot of the battlefield. “It’s very painterly, inspired by the wartime paintings in the National Gallery,” commented Cohen. “We rendered out some of the topography that was created for the battle sequence, and then painted on top of that.”

A Round-Up of Regency Magic

Jonathan Strange’s manipulation of the elements during the Battle of Waterloo is characteristic of the way magic is portrayed throughout the series. Referred to by the characters as “practical magic”, these supernatural spectacles of the Regency era are earthy and visceral – no Harry Potter pyrotechnics here.

“That comes from the book,” Deguara asserted. “It was a key part all the way through: if you want to use magic, you have to negotiate with the elements. Norrell has to read about it from a book, whereas Strange has more of a natural feel for it.”

Some of the other magical set-pieces featured in Jonathan Strange and Mr Norrell include:

Mr Norrell brings the statues of York Minster to life

Milk delivered thirty shots for the York Minster sequence. Their cast of animated statues included a line of seven stone kings, musicians and a Latin-speaking bishop. Bertie Carvel stepped briefly out of his role as Jonathan Strange to perform as the bishop while wearing a green chromakey leotard. His presence on set gave Dr Foxcastle (Martyn Ellis) a physical presence to react to, and provided Milk’s animators with crucial reference for the statue’s performance.

Jonathan Strange conjures a herd of giant sand-horses

Though comprising just eight shots, the sequence offers considerable spectacle, from an aerial shot pursuing cracks racing across the beach, to the explosive impact of the galloping sand-horses with a stranded warship. The sand-horses themselves – modelled to combine the features of both sleek racehorses and sturdy shire horses – were rendered as volumes, enhanced with particle effects and rigid body simulations.

Mr Norrell creates a fleet of illusory rain-ships

Answering director Toby Haynes’s request for a sequence that resembled a Turner painting, the Milk team combined live-action rowing boats (shot against greenscreen in a Yorkshire pond), simulated ocean environments and CG ships. Swirling displacement effects and interactive rain reinforced the ghostly navy’s subtle, dreamlike appearance.

Jonathan Strange creates a road for British troops

A close-up shot of stones spawning outwards from a central point – dubbed the “popcorn shot” – was created with a rigid-body simulation in Houdini. Matte painting techniques, combined with a CG dust trail, were used to show the road extending rapidly over distant hills.

Small Screen, Big Ambitions

Jonathan Strange and Mr Norrell contains more visual effects shot than many feature films, even allowing for the show’s seven-hour running time. Squeezing such a VFX quart into the pint pot of a television budget demanded precision planning.

“It’s a massive logistics and communications exercise,” Cohen observed. “We had pockets of people working all over the place for months at a time. They would park a certain piece of work, then come back to it weeks later.”

Just as important as being organised was being able to roll with the punches. “You have to pre-plan as much as you can,” Deguara agreed. “But when you get out on set, obviously things change and you have to adapt. Then we would all get in a room and have serious chats about an edit that might be five or six shots over what it should be. That’s when you have to make hard decisions.”

Hernandez added: “We were compromising to stay in budget, so whenever the director said, ‘I want this,’ half the time we would have to say, ‘You can’t afford it.’ We did a lot of stretching to make everything look good.”

Reflecting on the series as a whole, Cohen concluded, “We went on quite a journey. It was a very collaborative and enjoyable process for eighteen months, and we’re all very proud of it. From Peter Harness putting the words on the page, to Toby’s seven hour marathon of shooting it, there was a feeling all the way through of serving the material, and not letting it down.”

Jonathan Strange and Mr Norrell is currently airing on BBC America in the US, and BBC One in the UK.

Special thanks to Jenny Burbage. “Jonathan Strange & Mr Norrell photographs copyright © 2015 by BBC Television.