Wang Zhen
In July 1449, Esen Taishi launched a large-scale, three-pronged invasion of the Ming with his puppet khagan Toqtaq-Buqa. He personally advanced on Datong (in northern Shanxi province) in August. The eunuch official Wang Zhen, who dominated the Ming court, encouraged the 22-year-old Emperor Yingzong of Ming to lead his own armies into battle against Esen. The size of Esen's army is unknown but a best guess puts it at some 20,000 men. The Ming army of about 500,000 was hastily assembled; its command was made up of 20 experienced generals and a large entourage of high-ranking civil officials, with Wang Zhen acting as field marshal.