Hongwu (Chinese: 洪武; pinyin: Hóngwǔ; Wade–Giles: Hung-wu; lit.

'vastly martial'; 23 January 1368 – 5 February 1399) was the era name (nianhao) of the Hongwu Emperor (reigned 1368–1398), the Chinese emperor who founded the Ming dynasty that ruled China from 1368 to 1644.

On 23 January 1368 (Wu 2, 4th day of the 1st month), Zhu Yuanzhang proclaimed himself emperor of the Great Ming dynasty in Yingtian Prefecture, with the era name "Hongwu".

On 30 June (16th day of the 5th leap month), Imperial Grandson-heir Zhu Yunwen ascended the throne as the Jianwen Emperor.

[2][4] According to Xia Xie (夏燮)'s Ming Tongjian (明通鑑), since Zhu Di had started his rebellion at Beijing in 1399 (Jianwen 1), he had begun restoring the Hongwu era name in his conquered areas, and after the Jingnan campaign, he had ordered the whole country to reuse the Hongwu era name.