The Hunger Games director thoroughly researched American farmer and soldier Newton Knight, who led a band of Confederate army deserters during the American Civil War, for the new movie, and decided to stick as close to historical fact as he could while filming in the Mississippi swamps.

"The first responsibility we have is to be truthful," Ross tells WENN. "I think that we do more social good by being honest about a period in American history like the Civil War, that maybe lost.

"You can say the same about field hospitals - did you really need to show that much blood and stumps? A half truth is not the truth. I did three years of research into a world of young farmers, who were living on their own under very tough conditions. Am I going to worry about how my culture is going to receive that or am I going to tell the truth?

"Once I decided to tell the truth, there's no turning back from that. There are so many lies about this era that need to be unveiled. So the first step is to tell the truth and if I don't have that then we're all in a lot of trouble and the movie isn't worth making."

The new film, starring Matthew MCConaughey as Newton Knight, hits U.S. cinemas this weekend (24-26Jun16).