Emperor Qianwen acceded to Zhu Xiangsheng's wish, arranging for him to gain experience in the military, while also regarding him with more esteem than before. He felt that Zhu Xiangsheng was not afraid of hardships, was practical, and, lacking a prestigious background, would not hold overly ambitious desires. Such a person, once well cultivated, could indeed be an asset to the Crown Prince.
Crown Prince Zhu Xiangchang was pure and filial. His mother, Empress Yuan, died when he was three, and he was brought up personally by Emperor Qianwen. Despite trying many methods, perhaps due to his nature, the emperor failed to change the Crown Prince's gentle and benevolent character.
If this eldest son could wholeheartedly assist the Crown Prince, then Emperor Qianwen would be much more at ease.