Ascension
The Hongwu Emperor was long-lived and survived his first heir, Zhu Biao, Prince of Jin. He worried about his succession and issued a series of dynastic instructions for his family, the Huang Ming Zu Xun. These instructions made it clear that the rule would pass only to children from the emperor's primary consort, excluding the Prince of Yan in favor of his nephew, Zhu Biao's son. When the Hongwu Emperor finally died on 24 June 1398, this teen-aged nephew succeeded as the Jianwen Emperor. In direct violation of the dynastic instructions, the Prince of Yan attempted to mourn his father in Nanjing, bringing a large armed guard with him. The Imperial Army was able to block him at Huai'an and, given that three of his sons were serving as hostages in the capital, the prince withdrew in disgrace.
The new emperor's harsh campaign against his weaker uncles (dubbed 削蕃, "Weakening the Marcher Lords") made accommodation much more difficult, however: Zhu Di's full brother was arrested and exiled to Yunnan; the Prince of Dai was reduced to a commoner; the Prince of Xiang committed suicide under duress; the Princes of Qi and Min were demoted all within the later half of 1398 and the first half of 1399. Faced with certain hostility, the Prince of Yan "fell ill" and then "went mad" for a number of months before achieving his aim of freeing his sons from captivity to visit him in the north in June 1399. On 5 August, the prince declared that his nephew had fallen victim to "evil counselors" (姦臣) and that the Hongwu Emperor's dynastic instructions obliged him to rise in arms to remove them, a conflict known as the Jingnan Campaign.
In the first year, the Prince of Yan survived the initial assaults by superior forces under Geng Bingwen and Li Jinglong thanks to superior tactics and capable Mongolian auxiliaries. He also issued numerous justifications for his rebellion, including questionable claims to have been the son of Empress Ma and bold-faced lies that his father had attempted to name him as the rightful heir, only to be thwarted by bureaucrats scheming to empower Zhu Biao's son. Whether because of this propaganda or for personal motives, the prince began to receive a steady stream of turncoat eunuchs and generals who provided him with invaluable intelligence allowing a hit-and-run campaign against the imperial supply depots along the Grand Canal. By 1402, he knew enough to be able to avoid the main hosts of the imperial army while sacking Xuzhou, Suzhou, and Yangzhou. The betrayal of Chen Xuan gave him the emperor's Yangtze River fleet; the betrayal of Li Jinglong and the prince's half-brother Zhu Hui opened the gates of Nanjing on 13 July. Amid the disorder, the imperial palace quickly caught fire: the Prince of Yan enabled his own succession by claiming three bodies – charred beyond recognition – as the young emperor, his wife, and their infant son but rumors circulated for decades that the Jianwen Emperor had escaped dressed as a monk.
Having captured the capital, the Prince of Yan now left aside his former arguments about rescuing his nephew from evil counsel and voided the Jianwen Emperor's entire reign, taking 1402 as the 35th year of the Hongwu era. His own brother Zhu Biao, whom the Jianwen Emperor had posthumously elevated to emperor, was now posthumously demoted; Zhu Biao's surviving two sons were demoted to commoners and placed under house arrest; and the Jianwen Emperor's surviving younger son was imprisoned and hidden for the next fifty-five years. After a brief show of humility where he repeatedly refused offers to take the dragon throne, the Prince of Yan accepted and proclaimed that the next year would be the first year of Yongle. On 17 July 1402, after a brief visit to his father's tomb, Zhu Di was crowned emperor of the Ming at the age of 42. He would spend most of his early years suppressing rumors and bandits.
Read more about this topic: Yongle Emperor