Hong Taiji renamed his state from "Great Jin" to "Great Qing" and elevated his position from Khan to Emperor, suggesting imperial ambitions beyond unifying the Manchu territories. Hong Taiji then proceeded to invade Korea again in 1636. Meanwhile, Hong Taiji set up a rudimentary bureaucratic system based on the Ming model. He established six boards or executive level ministries in 1631 to oversee finance, personnel, rites, military, punishments, and public works. However, these administrative organs had very little role initially, and it was not until the eve of completing the conquest ten years later that they fulfilled their government roles. Hong Taiji staffed his bureaucracy with many Han Chinese, including newly surrendered Ming officials, but ensured Manchu dominance by an ethnic quota for top appointments. Hong Taiji's reign also saw a fundamental change of policy towards his Han Chinese subjects. Nurhaci had treated Han in Liaodong according to how much grain they had: those with less than 5 to 7 sin were treated badly, while those with more were rewarded with property. Due to a Han revolt in 1623, Nurhaci turned against them and ordered that they no longer be trusted and enacted discriminatory policies and killings against them. He ordered that Han who assimilated to the Jurchen (in Jilin) before 1619 be treated equally with Jurchens, not like the conquered Han in Liaodong. Hong Taiji recognized the need to attract Han Chinese, explaining to reluctant Manchus why he needed to treat the Ming defector General Hong Chengchou leniently. Hong Taiji incorporated Han into the Jurchen "nation" as full (if not first-class) citizens, obligated to provide military service. By 1648, less than one-sixth of the bannermen were of Manchu ancestry. Claiming the Mandate of Heaven Hong Taiji died suddenly in September 1643. As the Jurchens had traditionally "elected" their leader through a council of nobles, the Qing state did not have a clear succession system. The leading contenders for power were Hong Taiji's oldest son Hooge and Hong Taiji's half brother Dorgon. A compromise installed Hong Taiji's five-year-old son, Fulin, as the Shunzhi Emperor, with Dorgon as regent and de facto leader of the Manchu nation. Meanwhile, Ming government officials fought against each other, against fiscal collapse, and against a series of peasant rebellions. They were unable to capitalise on the Manchu succession dispute and the presence of a minor as emperor. In April 1644, the capital, Beijing, was sacked