German director Wolfgang Petersen made his name internationally with the 1981 submarine drama Das Boot. Since then he's helmed such Hollywood action movies as In The Line Of Fire, Air Force One, and The Perfect Storm. Now he takes on perhaps the greatest story of them all, an adaptation of Homer's epic poem The Iliad. Relaying the legend of the Trojan War, the very epic Troy sees Petersen working with an impressive ensemble cast that includes Brad Pitt, Eric Bana, Orlando Bloom, Brian Cox, and Peter O'Toole.

Is The Iliad a story that's very close to your heart?

Oh, yeah. Absolutely. When I was a boy I became an Achilles fan because I was in a school where we learned old Greek and Latin, and then The Iliad came along and there was Achilles. And Achilles was for me like a James Dean or a Marlon Brando - he was the ultimate rebel. He just lived by his own rules and nobody else's, and he would not accept any kind of authority. He was my guy, he was wonderful. When you're 15 or 16, that's what you need.

So, you grew up with the story, but how did the film come together so many years later?

Now, so many years later, Warner Bros said they'd developed a story based on The Iliad and I really thought, Oh my God, this is what I want to do! I said if there's a script that's any good - we know it's a difficult thing to get the mighty thing of The Iliad into a screenplay - if it's any good, I want to do it. And boy, it was good. It was very good. And then right away, Brad Pitt said he wanted to play Achilles, and within a few weeks the whole project was already done. So I mean, from about two years ago till now, the whole thing was done. It's a very short period of time. So now we're sitting here talking about this movie and I had no idea that after reading it when I was 16 that this would eventually come to me. It was just like a dream. A dream come true!

Helen of Troy is famed for being the "face that launched a thousand ships", but you had to embark on a worldwide talent search to find her [Diane Kruger]. Did you deliberately steer clear of casting a well-known actress?

Yeah. Helen was very known in her time, but nobody had seen her - she was somewhere hidden in Sparta. That's why I thought it would be great to find a new face. There's no baggage there, she's just Helen from Sparta. It was a long, long search of course, and we went across the world. It was a very, very hard job to watch 3000 beautiful women [laughs]. No, I'm kidding. I didn't see all 3000, just 200 or so. I was slumped in my chair watching beautiful woman No.168, in that cynical mode and saying, "Who's she? That's only 212 ships. Not good enough. Next!" All of a sudden Diane Kruger popped up and I was upright in my chair. I said, "Oh my God. I think she could be it." She was so beautiful and a great actress, I mean, I was so moved by what she was doing. She had that thing in her eyes that you cannot explain, when you look right into the soul of somebody. The studio agreed after a bit of nudging, and arm-twisting, and nudging again - because a big name was on their wish list. But we insisted and the rest is history.

So what was the thinking behind casting Brad Pitt as Achilles?

It makes a lot of sense that you have a big superstar like Brad Pitt for Achilles, because Achilles was definitely a superstar, like a pop star, or a rock star of his time. And we needed a beautiful man like Brad because Achilles was such an attractive and beautiful looking man.

And Hector?

Actually it's a funny story because Diana [Rathburn, producer] said to me: "I saw somebody on the street and I think it was Eric Bana, who's doing Hulk right now, and he look great. He could play Hector." But I'd just seen Chopper, and he was like a monster, you know? Eric was 50 pounds heavier than he is now, so I said, "He should play Hector? What's wrong with you Diana?" And she was saying, "No, no. He's lost weight. He looks great." So he came to my office and it was wonderful. I mean, I fell in love with Eric immediately because he looked great. I like Australians also, and right away he was the character because he's such a noble guy and so honest. He talked about his family and his kids and so on. I thought, He is ideal for Hector. So you have a superstar [Brad Pitt] and an actor like Eric, who is not a star yet, but who will be, maybe, in two weeks?

Of course Orlando Bloom is another a star on the rise. How did you see him fitting into the part of Paris?

This guy walked into our room, here at The Dorchester, and he had this unbelievable smile on his face and all this black hair and I said, "Who's that?" And they told me that's the guy from The Lord Of The Rings, and I said "Who from The Lord Of The Rings?" I had no idea because I'd seen him with all this long blond hair. But he was so beautiful, young and smiling, and very clever I must tell you - the way he talked about the part of Paris. He absolutely saw that it was a risky part because Paris is a coward. But Paris was also a very famous man and all the girls loved him, because he was such a beautiful young playboy type. So Orlando Bloom for that part? Pretty good. Then later on when I saw downstairs how all these girls were outside the hotel screaming that Orlando is here, I said "OK, I think this is a good choice!" A very good choice.

Peter O'Toole is fantastic in the film. How important was it for you to have an actor of his status in the role of Priam?

From the very beginning, I had the feeling that since this is a movie in the tradition of the great David Lean films - at least I saw it like that - that it would be just a wonderful nod to these kinds of movies, and to David Lean, to get Peter O’Toole. But not only because of that. He is one of the great, great actors of all time, and with what he brings with him as actor - I think he's now 50 years in this business - he would add something to the role of Priam that probably no one else can. We met in this hotel here [The Dorchester] and it was just a wonderful experience; he was sitting there with his scarf around the shoulder and his endless legs everywhere. A real movie star! I was very impressed.

Is it true he asked you for the role of Achilles?

Ah, yes! [Laughs]