A proposal of force is met by the more cunning brother with the suggestion that they bring only a handful of men. They get horses, have them shod, and set out. Once they sneak into the prison, the captive brother says he is carrying too heavy a load of chain to escape.
When faced with a bold attack, the more resourceful brother suggests they send only a few men. They obtain horses, have them prepared, and sneak into the prison. Upon entering, the captive brother says he's carrying an excessive load of chains that would hinder his escape.