Werner Herzog is well-known for his penchant for the extreme. The idiosyncratic director has one of the more impressively diverse careers, helming everything from documentaries on unusual figures such as the so-called "eco-warrior" Timothy Treadwell in "Grizzly Man" to movies like "​​Bad Lieutenant: Port of Call New Orleans" and everything in between. Somewhere on that continuum sits 2006's "Rescue Dawn," Herzog's dramatization of a documentary he'd produced a decade prior with "Little Dieter Needs to Fly."

The film focuses on the experience of former U.S. Navy pilot Dieter Dengler who was shot down over the Laotian jungle during the Vietnam war. Dengler proceeded to undergo a truly incredible, and highly distressing, experience as a POW before making his escape, and Herzog obviously couldn't get enough of the tumultuous story, making Dengler the focus of two very different projects. In the case of his movie version, the director needed a cast that was willing to match his own enthusiasm for retelling the story as vividly as possible. Enter Christian Bale, who agreed to star in the film post "Batman Begins" and who, unbeknownst to him at the time, would almost wind up in a Thailand jail during filming.

How did Herzog manage to get the rising star to agree to join him on what would quite clearly be a testing shoot? He took him to drinks and gave him a test of his own devising.

'He Wanted To See If I'd Flinch'

As Bale recounted in a chat with Entertainment Weekly, Herzog sat down with the actor and made as clear as possible what the role would require. The film would, of course, tell the story of Dengler being held captive and all the trials that came with it. From eating snakes and maggots to being dragged along by a water buffalo (all of which Bale did for real), the stunts and events in the film were designed to provide an unflinching look at what the real-life Dengler and his fellow prisoners went through.

During Herzog and Bale's meeting, the director made sure not to sugarcoat his pitch. As the actor recalls:

"He was just trying to push my buttons and see how I reacted. He just wanted to see if I flinched, basically. He does that a lot with people."

No doubt Herzog's well-documented eccentricity and passion for the extreme played into his button-pushing during the meeting. But it seems the director was also cognizant of the fact that Bale would have to undergo a lot worse than Herzog's prodding if he was to survive the shoot. Either way, the future star of the movie seemingly wasn't fazed by the meeting, maintaining that he remained interested by the main character of the film being a clear "mixture of Dieter and Werner." What's more, it seems the "Dark Knight" star wanted to get a glimpse of Herzog's notorious personality up-close, saying: "knowing Werner's reputation, I wanted to see for myself."

Some Things Were Too Much For Even Bale

Considering the central cast, which also included Steve Zahn and Jeremy Davies, would have to lose considerable weight before a single scene was even shot, Herzog was right to test Bale before he took on the starring role. The director approached the shoot by having Bale and his fellow POW actors lose weight before the movie got underway to allow the crew to get the jungle scenes shot first. The actors would then regain their weight to shoot the prior scenes later in the schedule. And that was just the beginning.

Besides the aforementioned maggot and snake eating, Bale would even be encouraged to perform a helicopter stunt that even he, as committed a performer as he is, pushed back on. Bale recounted having to stand up to his director when Herzog was encouraging him to take part in the filming of his helicopter rescue which producers had advised against due to safety concerns. Still, that confrontation doesn't seem to have soured the sometimes over-enthusiastic Herzog, who told The New York Times after the fact that Bale was "the most disciplined, wonderful man … he did things that an actor of his caliber normally would not do … It's unbelievable."

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