Most of the scenes in Steven Spielberg's World War I epic War Horse use real horses, but a couple of particularly animal-unfriendly scenes required the use of animatronics.

Wired.co.uk discovers how special effects company Neil Corbould SFX, which has created mind-blowing effects for movies such as Gladiator, The Day After Tomorrow, The Fifth Element and Saving Private Ryan, created its startlingly realistic steed.

Adrian Parish, one of the mechanics who worked on a team of more than a dozen sculptors, puppeteers and engineers to bring the horse to life, explained: "Our brief was to provide a realistic horse that could sit in mud and barbed wire for an extended period of time, something that would not be safe or possible with a live animal."

One scene featuring the animatronic horse was where equine protagonist Joey gets caught in barbed wire in no man's land between the German and British trenches. The horse was placed on a very busy, wet and muddy set in a disused airfield in Surrey designed to look like the battlefield of Somme during World War I.

The team decided it was best to build a puppet that could be manipulated from beneath using control rods. As the mechanism was to be buried underneath the creature, they decided to avoid complex hydraulics and keep it simple so that there were fewer opportunities for technical failure.

Underneath the horse puppet was a box in which four puppeteers could sit and manipulate the creature's body and head, creating movements including breathing. "A household kettle was also installed in the box that had tubes running between it and the nostrils to give the illusion of condensed breath," Parish added.

The head part of the puppet was radio controlled and contained 25 servo motors to control the eyes, eyelids, ears, brows, lips, nostrils and jaw. The head alone took three puppeteers to control – one to operate the eyes, one for the mouth and one for the ears. This team didn't have to cram into the buried box, but were above ground, able to observe their handiwork.

The skin was created using a full-size clay sculpture of the horse. A molded fiberglass shell was covered in a centimeter-thick layer of clay, which was then covered in another layer of fiberglass. Once all the layers had set, the clay was removed from between the two fiberglass layers and replaced with an injection of foam latex. The skin's fine seams had to be very carefully removed before painting and the whole thing was fitted over an articulated fiberglass skeleton.

The final stage was to flock the horse to give it its shiny fur. This process involved applying a layer of polyurethane glue, onto which small artificial hairs were applied. An airbrush was then used to blow the hair into the desired direction before the glue set. The final touches came with the addition of fine hairs around the mouth, ears and brows that were set individually. Then the eyelashes were applied and the whole thing was airbrushed once again.

Once the puppet body and animatronic head were complete, they were set in position and dressed with barbed wire and fake blood and scars. The animatronic horse is as impressive as the puppets used in the stage production of War Horse, seen in a TED talk here.

Watch the staggeringly realistic head (before the addition of fur) and body in action in the videos embedded in this post.