Kevin Costner on why he never gave up on his 35-year passion project 'Horizon: An American Saga': 'It's hard to fall out of love. I don't do that.'

Warner Bros. debuted the full-length trailer for the big-budget, multi-film franchise that Costner has been developing for over 30 years.

• The full-length trailer for Kevin Costner's "Horizon: An American Saga" has been released.
• The actor has directed, cowritten, and produced the Western epic, split into four films.
• Featuring an ensemble cast, the films are set against the backdrop of Civil War-ravaged America.

Warner Bros. has debuted the first full-length trailer for Kevin Costner's big-budget epic, "Horizon: An American Saga," a multi-film franchise that the actor has been developing on and off for most of his career.

Featuring a large ensemble cast — including Costner himself — the films are set against the backdrop of Civil War-ravaged America, a subject matter Costner previously explored in the Academy-Award-winning "Dances With Wolves."

"There's no army on this earth that's gonna stop those wagons coming and them doing as they want to," comments an army general character played by Danny Huston as dozens of prairie wagons symbolizing the expansion of the American West fill the screen.

The ambitious cinematic experience will be split up into four films, with the first two chapters arriving in theaters domestically on June 28, 2024, and August 16, 2024, respectively.

The films, cowritten by Costner and Jon Baird, will explore the "lure of the Old West and how it was won — and lost — through the blood, sweat, and tears of many," according to an official synopsis.

Spanning the four years of the Civil War, from 1861 to 1865, the horse opera is expected to be a hit with the audience Costner cultivated from his role on Paramount Network's "Yellowstone."

In a press conference held before the trailer launch and attended by Business Insider, Costner stressed how important the project he initially conceived in the 1980s was to him and why he never gave up on it

"It's hard to fall out of love. I don't do that," Costner, who recently finalized his divorce from his wife of 19 years, Christine Baumgartner, said.

"I think things that have a classic feel, they don't fall out of touch either," he continued. "I think that they exist in any decade. That's the opportunity we have in cinema, to make something that lasts past its opening weekend."

Costner, who has partly funded the project himself, mortgaging a 10-acre California property and investing $20 million, joked: "When no one wanted to make the first one, I got the bright idea to make three more. I don't know what's wrong with me."

He went on to highlight the talent of the film's sprawling cast, which includes Jamie Campbell Bower, Sienna Miller, Sam Worthington, Jena Malone, Abbey Lee, Ella Hunt, Luke Wilson, and his son Hayes Costner, who will make his debut in the film.

"These parts spoke to actors, and they all wanted to come west with me," he said of the names who chose to saddle up for the saga.

"I love women in cinema," he continued after singing the praises of Miller, Malone, and Hunt, who play prominent roles in the films.

Asked about what he hopes audiences will take away from the films, Costner said: "I hope that people feel that were taken somewhere. You know, the oldest profession, you know, besides that gal thing, is telling stories around a fire. And we all want to hear a good one."

Watch the trailer below.