Morton plays a woman whose soldier husband dies in combat and one scene shows her character being told the tragic news.
The 34 year old admits she did little preparation for the shoot, as she wanted to convey her natural emotions - and she hopes it gave the war movie more authenticity.
She tells Britain's Total Film magazine, "I didn't talk to any war widows beforehand because I thought I have to go through this the way it would happen. I would've had a premeditated idea of how I would behave if I was told that my husband had died.
"We didn't rehearse that scene - we went straight in, so you have the real reaction that I would give were I in that situation."