For actor Michael Cox, he and fellow performers in “War Horse,” which opens Tuesday at the Saenger Theatre, are charged not only with creating their own characters.

They also must assist in the realization of the play’s central figure: a life-sized, fully functioning horse puppet named Joey.

The 2011 Tony Award Winner for Best Play, Nick Stafford’s “War Horse” follows the relationship between Joey and his first owner, Albert, played by Cox, through the tragedy of World War I.

Taking place both in England and across Europe, the epic tale follows its protagonist horse through vast countrysides, shattered villages and even a full-on cavalry charge.

In a show that includes barnyard animals, rolling tanks and barbwire-covered battlefields, it is very easy for an actor to be swallowed by the unfolding theatrical magic.

Furthermore, the actors were required to perform a double duty of sorts.

“The human actors are also puppeteers in that our interactions, the actors reactions, assist in making Joey real,” the actor said.

He pointed out that Joey’s puppeteer handlers rehearsed for two weeks before their human counterparts arrived.

Therefore, the company met the actualized Joey on their first day of rehearsal.

“We came in, and Joey just walked into the room,” Cox said. “It gave me the chills.”

The son of a veterinarian, Cox, 27, was in awe of what had been created.

“It seemed so real,” he said. “I could almost smell it.”

Essentially, Joey became simply another member of the cast.

In a TED Talk about the creation of Joey, Adrian Kohler, of the Handspring Puppet Co., pointed out that “an actor struggles to die onstage, but a puppet struggles to live.”

Commissioned by the National Theatre to create the horse, Kohler and partner Basil Jones sought a verisimilitude never before seen on stage.

A complex network of a wooden skeleton, mechanical joints and wire tendons, Joey had to be designed to allow for full movement and be sturdy enough for a rider to mount him.

Three puppeteers/actors collaborate in the creation of Joey. Despite having individual assignments, the trio that bring the horse to life work together to give the illusion of a singular entity.

The dynamic process demands a complete physical commitment to the endeavor that includes the hand operation of a series of controls activating the smallest details.

Standing alongside the horse, the first operator is responsible for the head and the control of Joey’s ears, which on a horse are crucial for communicating emotions.

The second commands the front legs and essentially functions as Joey’s heart. From that position, the performer enables functions such as breathing that are realized through the bending of the legs.

Finally, along with being in charge of the back legs, the third puppeteer handles the other great indicator of emotion: the tail.

Those separate operations must then achieve a unison that makes the puppeteers all but disappear.

Complicating the matter is the fact that the three horsemen cannot speak to one another while on stage, because each wears a microphone. They must create a series of naturalistic sounds matching Joey’s complicated movement, and this precludes any verbal communication.

With the disparate actions choreographed to become Joey, the final element in creating the reality of the horse comes from its encounter with its human counterparts.

In Cox’s mind, the trick came from understanding that his and Joey’s journeys were one and the same.

“Like Joey, Albert is a loner. They find each other and must find the courage to overcome their fears. They grow up together and are left confused by their split.”

Focusing on that was the key, because it prevented him from being swept up into the spectacle and allowed him to “settle into the world, forget what was behind it.”

That “settling in” allows the actor to focus on the whole point of the tale.

“From farm to battlefield, I need to get back to Joey.”

Jim Fitzmorris writes about theater. He can be reached at shcktheatre@aol.com.