Colin Farrell might be jaded but he doesn't sound it. It's 10.30pm on a miserable Saturday night in Dublin, he's just finished a round of interviews after flying in from a movie set in Prague and within 60 seconds of sitting down in front of a festival audience he's won everyone over with his blend of charm, scattergun wit and colourful language. Rapturously received after a screening of his breakthrough film 'Tigerland', Farrell seems more intent on having fun than soaking up the plaudits." 'Tigerland' opened on about four screens in the States," he says. "I'm just glad there's more than ten people in the room."

Farrell may joke about the film's fate in the US but whether on four screens or 400, his performance did not go unnoticed. He's won the Best Actor Award from the Boston Society of Film Critics and picked up roles in a handful of films (including Steven Spielberg's 'Minority Report') on the back of it. 'Tigerland' has also, reportedly, helped give him a price tag of $2.5m per picture. Set in a Louisiana training camp, it follows the experiences of a group of volunteers and conscripts as they 'prepare' for the Vietnam War. Farrell plays Roland Bozz, a Texan drifter who throws more than a few spanners into the army's killing machine with his answer back ethos and contempt for the powers that be. Playing the American lead in a character – not bullet – driven war movie was a big step up for the former 'Ballykissangel' actor, but also marked a major departure for the film's director, Joel Schumacher. Best known for Hollywood outings like 'The Client' and 'Batman Forever', for 'Tigerland' Schumacher traded multiple cameras, big budgets and bigger names for a handheld 16mm, a 28-day shooting schedule and a cast of unknowns.

"The only reason I'm here now and the only reason I've done anything afterwards is because of him," says Farrell of the director he's worked with again on the upcoming thriller 'Phone Booth'. He's really open, really lovely and one of the bravest men I've ever met. The producers were going 'Ballykisswhat'? Bozz is Texan - the lead's got to be a star'. Joel just fought for me." Farrell met the director at a casting session in London when he was auditioning for a supporting role. By that stage he had seen 40 actors, but sensed that the Dubliner could have what it takes for the lead. They talked briefly before Schumacher sent him away to study the part of Bozz. Back home in Dublin, Farrell and his sister put his audition down on videotape and sent it to LA. Two weeks later he followed the envelope out West.

With the role in the bag, Farrell began researching Bozz. He already had much in common with the character, having done his fair share of wandering (a year in Australia when he was 17) and also dropping out of further education (after one year at the Gaiety School of Acting). The real test would be the Southern drawl. He went to Toronto, worked with a voice coach and then spent a month by himself travelling around Texas soaking up the atmosphere and accent. When he returned, Schumacher had arranged two weeks of boot camp in Florida for his cast. Farrell and 24 other actors were put through their paces by a group of drill instructors, among them a Vietnam veteran, Michael Stokey. "We ate rations, stayed out late, were woken up at 2am and taken out and shown how to take apart an M16 and put it back together," he recalls. "Michael Stokey's job was basically to teach us and train us, take us through, make us run. I went into the boot camp thing thinking I was going to mess around and be as cocky and cheeky as I could, but when I got there I realised the only reason he was there was to actually help us. He still pushed us, roared at us and woke us up way too early for my liking, but I decided to learn as much as I could off him and he was amazing."

Listening to Farrell talk about 'Tigerland', it becomes obvious that the interaction between actors and crew went far beyond what normally occurs on a film set. He talks about how the to the wire shooting schedule helped everyone to bond and how the film's documentary feel made the players raise the stakes in every scene. The cast remain close and Farrell is the godfather to the son of his co-star Shea Wingham. "What you see was the most amazing experience. Joel wanted to get back to basics, he wanted to get back to telling a story. For most films you perform for the camera, the camera is there and you have to tell the story to it. Joel allowed the camera to find what was happening in the story. There were no rules, no guidelines, threw were no marks to hit, you just did whatever you wanted to do. Joel trusted you."

But while critics have remarked on the power of the ensemble cast – and in particular, Farrell – many have been less complimentary about 'Tigerland's' plot. Farrell however, is nonplussed. "I remember the New York Times wrote the worst review I read on 'Tigerland'. They said it was clichéd and all the characters were too well defined. They kind of criticised all the things that made me like it: if you're going tell a story about the 55,000 men that died and the thousands that fought, you have to pick five or six characters. I'd don't think you could ever get sick of a story that has so much loss and so much pain. Hopefully you could tell a thousand of them and there would be something new in every story."

Farrell has returned to fatigues for his latest film, the Prague-shot 'Hart's War', in which he stars alongside Bruce Willis. "I play a guy who's a bit wet behind the ears, very privileged, a third year Yale Law student. He's in a chateau, a cigar lighter – that kind of solider. He gets captured and it's about him becoming a man." "Again, like this film," he says pointing to the screen, "it's based around historical events, so you hope you're doing it justice." If his turn in 'Tigerland' is anything to go by Farrell has nothing to worry about.

Harry Guerin