Context : Originally, at the end of Nurhaci's reign, Hong Taiji got hold of the two White Banners, but after Lady Abahai's death, he switched his two banners with Dorgon and Dodo's two Yellow banners (Nurhaci gave his two Yellow Banners to the two). 
Subject : Hong Taiji 
Relation : date of death
What was the death date of Hong Taiji?