Question: Robbie's soldier friend (I think his name was Nettle) was so calm and compassionate with him. He said that the hiding place was in reality the beach cottage and he protects Robbie from the angry soldiers. Did he do that because he saw how sick he is and probably knew, deep inside, that Robbie will not survive the night until the evacuation, and wanted to give him a peaceful end? Why does he take Robbie's letters and pictures with him?
Answer: I think he realizes that Robbie most likely won't make it. He takes the letters so that he can get them back to his loved ones. He probably knows that there is a last goodbye to someone (his girl/his mother) in them. And, if nothing else, even if his body doesn't make it back to them, they have a piece of him to cherish.