By 1636, Nurhaci's son Huang Taiji renamed his dynasty from the "Later Jin" to the "Great Qing" at Mukden, which had fallen to Qing forces in 1621 and was made their capital in 1625. Huang Taiji also adopted the Chinese imperial title "huangdi", declared the Chongde ("Revering Virtue") era, and changed the ethnic name of his people from "Jurchen" to "Manchu". In 1638 the Manchu defeated and conquered Ming China's traditional ally Joseon with an army of 100,000 troops in the Second Manchu invasion of Korea. Shortly after, the Koreans renounced their long-held loyalty to the Ming dynasty.