建文帝

His father, the crown prince 朱标, died before 朱元璋, so the throne passed to the grandson, 朱允炆, in 1398. His moves to strip his uncles the princes of their power (削藩) drove 朱棣 to rise against him, and when Zhu Di's army entered 南京 in 1402 the palace went up in flames. Whether he died in the fire or escaped, some say as a monk, has never been settled.

建文 was his reign name, hence 'the Jianwen Emperor'. Zhu Di struck those years from the calendar, counting them as the last years of his father's reign, and the reign name was restored only in 1595.