The Moneyball star loves re-creating battles with 10-year-old son Maddox.
The Hollywood hunk even splashed out £8,000 on suits of armour so they can take really get into character in the specially organised battles.
'Brad has always been passionate about history,' an insider reportedly revealed.
'Maddox was really interested in wars but hated all other aspects of the subject,' continued the source, 'so Brad hatched a plan for them to dress up and go to re-enactment days.
'He bought suits of armour and even special weapons,' the source explained. 'Now all the kids are really interested in history.'
Brad's wife Angelina Jolie recently divulged that Brad loves teaching Maddox.
'Brad has always had this incredible bond with Mad, who's very smart, and Brad loves teaching him about history and art and culture,' she told OK! magazine.
'It's an amazing thing to watch them together.'