Yongle Emperor (Zhu Di)

Zhu Di (1360-1424), who ruled as the Yongle Emperor from 1402 to 1424, took the Ming throne by force from his nephew and presided over one of the most expansive reigns in the dynasty's history. The fourth son of the founding Hongwu Emperor, he was enfeoffed as Prince of Yan with his seat at Beiping (modern Beijing), where he gained long military experience campaigning against the Mongols. When his father bypassed the surviving sons in favor of a grandson, the Jianwen Emperor, and the new ruler began stripping the princes of their power, Zhu Di rebelled in 1399. The three-year Jingnan campaign ended with the capture of Nanjing in 1402, the disappearance of the Jianwen Emperor, and Zhu Di's accession.

He legitimated the seizure harshly, purging officials loyal to his predecessor and erasing the Jianwen era from official records, while presenting himself as the true continuator of his father's order. His government nonetheless undertook projects of unusual scale. He transferred the principal capital from Nanjing to his old power base, renamed Beijing, where construction of the imperial palace complex later known as the Forbidden City was completed in 1420; the city remained China's capital, with brief interruptions, into the modern era. The Grand Canal was rebuilt to provision the northern capital, and the enormous Yongle Encyclopedia was compiled under imperial sponsorship.

Abroad, the reign is best known for the maritime expeditions commanded by the eunuch admiral Zheng He, which between 1405 and 1424 carried large fleets through Southeast Asia and the Indian Ocean as far as Arabia and East Africa, collecting tribute embassies and projecting Ming prestige. The emperor also annexed Vietnam in 1407, an occupation his successors eventually abandoned, and personally led five campaigns into Mongolia.

Zhu Di died in 1424 while returning from the last of these steppe campaigns and was succeeded by his eldest son, the Hongxi Emperor. Assessment of his reign has long balanced the violence of his usurpation and purges against the durability of his works: the northern capital, the canal-based supply system, and the precedent of an emperor ruling from the Mongol frontier all outlasted him by centuries.