David Ayer is a director who demands a certain level of realism in his movies; if the actors are portraying cops or soldiers then he'll train them physically to the level where they look natural holding firearms. He went to further extremes on Fury, where he made the set intentionally miserable to get the cast into the mindset of World War 2 soldiers. He made sure actor Logan Lerman who played the new recruit was made to feel as miserable as humanly possible, so hed look appropriately downtrodden on screen. He also encouraged them the cast to fight each other as a way of relieving tension, and building brotherly trust. Brad Pitt and Shia LaBeouf got into regular fights over very little, though they both insist it was to the benefit of the movie. Ayer also made them eat, sleep and go to the toilet inside of their crammed tank, like the real soldiers would have to do. With those kinds of conditions, fist fights are almost inevitable.
