Father tells Bruno he is pronouncing "the Fury" incorrectly.How should it be said?What is the author suggesting by having Bruno mispronounce it in this way?

Hitler's title was the Führer, also spelled Fuehrer. The author has Bruno call his Fury to add a sense of innocence to Bruno, an innocence that is quickly eroding. The word "fury" also reflects Hitler’s blind anger with the world.