Its amazing how bogus details can persist in the face of hard data.
It is a slightly odd advertisement for the school, as if they had some special need to explain that they weren't military. Did the school have a reputation for 'straightening out' wayward sons? Recently, magazines like the New Yorker tended to have ads for schools that dropped all kinds of hints.
$950 tuition was nothing to sneeze at back in 1921.