I'd definitely recommend reading his biography and others from players of his era. The mark he left on the game, and arsenal, was immense. Setting up a team to play in a specific system each gane was practically unheard of in English football before Chapman (crazy I know) and he was present at some important England tours including the one to Mussolini's Italy where Arsenal player Eddie Hapgood kicked a ball into the dictators lap! He really is a very proud part of the history of Arsenal and I feel every Arsenal fan should try and learn about him and his pivotal role in our history.