Sam Claflin spoke with four former soldiers who suffered with PTSD to research his role in 'Journey's End' and he admits it was an "eye-opening" experience.
The 31-year-old actor stars in the movie adaptation of RC Sheriff's classic play as alcoholic serviceman Captain Stanhope and he had the honour of meeting with men who had served in the armed forces.
Claflin is most famous for his performances in 'The Hunger Games' franchise and the Brit hopes his fans will go to see his latest movie and get a lesson on World War One.
Speaking to Time Out London magazine, Claflin said: "I hope people want to learn what happened in World War One, and want to learn more about what servicemen experience now. We were fortunate enough to sit with four ex-soldiers who shared their experiences with PTSD. It was the most eye-opening few hours I've ever had."
The film - helmed by Saul Dibb - follows C-company arriving to take its turn in the front-line trenches in France led by Captain Stanhope.
As the German forces move in, the officers -played by Paul Bettany, Stephen Graham and Tom Sturridge - as well as their cook (Toby Jones) distract themselves with talk of food and their past lives.
However, Stanhope continues to soak his fear in whisky but when a young new officer Raleigh (Asa Butterfield) arrives fresh out of training, he is forced to serve under Stanhope - his former school house monitor and object of his sister's affections.
Each of the men are trapped in the trenches with the tension rising and the imminent attack draws near.
Claflin learned how to play an alcoholic at drama school, but after watching his performance in 'Journey's End' back he was worried he had gone "too far" in trying to mimic somebody inebriated.
He said: "Someone at drama school told me that the key to drunk acting is to not play drunk. There are moments watching the film back where I wince, 'Did I go too far there?' but that's the truth of my character, he doesn't know when to stop.
"I had to keep a diary on set so I knew how drunk he was. On the 'Riot Club', all our characters were on drugs or drunk, so we were all finding the atmosphere together, but here it was just me. I almost had to take myself off at times."