Johnny Cash was one of the most iconic performers country music has ever seen. The 2005 biopic 'Walk the Line' brought his life story to the big screen, winning an Oscar and raking in a box office fortune -- despite the fact that the star of the film had never sung before.

The script was written by James Mangold and Gill Dennis, drawn from Cash's two autobiographies. Mangold hired on to direct the film, but his choice to play Johnny Cash was a surprise to many -- including the actor himself.

Joaquin Phoenix wasn't sure he was the right choice for the role when he was first contacted about the project. He was a different size than Cash, and he had no background in singing.

"There are probably many people that were considered," he said. "Of course, I read a script and I have a list of 10 people that should do this instead of me, that are much more qualified. But I don’t know. You want to think it’s because Jim [Mangold] does research and knows how I work and knows that I would be really committed to this. But I don’t know."

Reese Witherspoon was cast as June Carter Cash, and she and Phoenix both had to do a lot of preparation before they could work on the film.Witherspoon spent hours studying June's voice and mannerisms, trying to look and sound like her.

“Well, [it was] nearly impossible so I just tried to be the best version of what I could be, because it was impossible to emulate her," she related. "And I’m sure on Joaquin’s part it was pretty difficult to emulate Johnny Cash. But we trained for five and a half months and learned to play instruments, record an album, and worked six or seven hours every day for five months on it. So you can’t say we didn’t try.“

The film's plot focused primarily on the romance between Johnny and June, which had many strikes against it -- the fact that Cash was married to his first wife, Vivian, when they met, June's marriages, and his terrible struggles with addiction. Using that as the impetus, the film wove a compelling tale that was part romance, part heartbreak, part cautionary tale -- all against a backdrop of classic country music.

Released on Nov. 18, 2005, the film was a runaway hit, earning more than $186 million at the box office.

The critics loved the film, too. "Phoenix and Witherspoon are dynamite, and their chemistry is palpable," wrote Rolling Stone. "Phoenix works miracles in showing the duality in a sensitive man his pals call John and a commodity even he calls Cash. And watch out for Witherspoon. . . her portrayal of June is astounding in its vitality and richness.This is award-caliber acting, deep and true."

That turned out to be prophetic. 'Walk the Line' was nominated for five Academy Awards, including Best Actor, Best Actress and Best Costume Design. Witherspoon won Best Actress, as many critics had predicted upon the film's release.

Phoenix was pleased that the story remained true-to-life. He'd spent an evening with Johnny and June, and was touched by the way they still related to each other after many years together.

"Most marriages and love affairs don’t last, and so it was nice to witness that first-hand and know that it wasn’t something that was just fictionalized and created by Mangold to kind of paint this perfect love story," he observed. "That it really was that perfect which I still, even having witnessed it, find it hard to believe. And I don’t know if that says something about my cynicism or what, but that was an amazing experience."