Zhu Gaochi's Life before the Throne
Zhu Gaochi was born in 1378, the eldest son of Zhu Di, then Prince of Yan, and was educated by Confucian tutors. He was heavy and in poor health, with little interest in soldiering, although he was said to be a fine archer. He preferred books and the company of scholars, and this set him apart from his father and from his ambitious younger brothers, Zhu Gaoxu and Zhu Gaosui.
He proved himself early. When his father rebelled against the Jianwen Emperor in 1399, Zhu Gaochi was left to hold Beiping (Beijing), and he defended the city against a far larger imperial army.
After his father took the throne as the Yongle Emperor, Zhu Gaochi was named crown prince in 1404. Through the long years when Yongle was away campaigning against the Mongols in the north, the crown prince governed in his place, first from Nanjing and later from Beijing, and so came to the throne with long experience of the imperial administration.
His brother Zhu Gaoxu, who had distinguished himself as a soldier in the civil war, never accepted his position, and the crown prince's supporters at court were often slandered and punished. In 1421 the minister of revenue, Xia Yuanji, was imprisoned for opposing another expensive campaign in Mongolia. In the same year Yongle ordered a halt to new treasure voyages, although Zheng He's sixth voyage, which had already sailed, was allowed to complete its mission.