"Maddox knows so much about tanks that when we first started on the movie, I was asking him for information," Brad told the Radio Times. "He has an extensive knowledge developed on his own since he was young."
The actor played an army sergeant commanding a Sherman tank and a five-man crew on a dangerous mission across enemy lines. Much of it was shot on set in Hertfordshire and Oxfordshire last year.
Maddox's six-year-old brother Knox was also fascinated by the shoot. "He loved the tank, and though he has no concept of war or what the tank's history is, he was so drawn to it. There is that inexplicable fascination that man has with machine."
Brad Pitt says Maddox has read so much about tanks he could help
In the interview, the 53-year-old revealed that he learned how to handle weapons from a young age. "I got my grandfather's shotgun when I was in kindergarten.
"There's a rite of passage where I grew up of inheriting your ancestors' weapons . . . My brother got my dad's."
He added that his father instilled in him "a profound and deep respect for the weapon".
It's been an exciting time for Maddox after his parents' wedding and meeting the Queen
Brad is currently criss-crossing the globe to promote Fury. On Tuesday, the star joined Shia LaBeouf at the New York premiere. He larked around greeting his young co-star with a kiss on the hand.
It's been an exciting time for the Jolie-Pitt clan. Following Brad and Angelina's wedding at their French estate, the family met with the Queen as the actress was invested as an honorary dame for her campaign against sexual violence.
After Hollywood's very own queen received her award, the couple's six children were called in to meet the monarch privately.