Following the suppression of his younger brother Duan’s rebellion – abetted by their mother, Lady Jiang – Duke Zhuang of Zheng discovered incriminating letters exchanged between them.
According to historical records, notably the Zuo Zhuan (Zuo’s Commentary) and Records of the Grand Historian (Shiji), Duke Wu of Zheng (Zheng Wu Gong) had two sons with his wife Lady Jiang.