両広総督
In 1822, Zhang Bao, aged 36, died near Penghu while serving as a colonel () in charge of the Penghu garrison. In 1824, Zheng Yi Sao returned to Guangdong with Zhang Yulin. In 1840, while living at Nanhai, Zheng Yi Sao filled charges against a government official, Wu Yaonan (), for having embezzled 28,000 taels of silver that Zhang Bao had handed over to him in 1810 for the purchase of an estate. The Viceroy of Liangguang at the time, Lin Zexu, petitioned the emperor to dismiss the case, which he did.