Josef wasn't Emma’s biological brother, but they had grown up together since they were kids. He relied heavily on her, and she was accustomed to having a shadow around her. Calling them siblings wouldn’t be an exaggeration.
But Josef had died during the battle. What was even more crucial was that his death was unjust. If he had fought and died for his village and his people, his death wouldn't have seemed so meaningless but the battle, although intense, failed to produce any meaningful results.