5 books · Ages 6–12
Children's Military History is a 5-book series for ages 6–12 by Baby Professor. Each book stands alone — start anywhere.
Start anywhere — each book stands alone.
That said, The Unofficial Christmas Truce of 1914 and Did the World War II Spies Have Super Cool Gadgets? are great first picks.
No particular order needed — browse and pick what catches your eye.