In 210 BC, after Qin Shi Huang died in Shaqiu (沙丘; south of present-day Dapingtai Village, Guangzong County, Hebei), Zhao Gao and Li Si, the Chancellor, secretly changed the emperor's final edict, which originally named Fusu, the crown prince, the heir to the throne.
In 207 BC, when rebellions broke out in the lands east of Hangu Pass, Zhao Gao became worried that Qin Er Shi would blame him, so he launched a coup in Wangyi Palace (望夷宮; in Xianyang, near present-day Xi'an, Shaanxi) and assassinated the emperor.
[clarification needed] This was very useful to Qin Shi Huang since he himself was always looking for ways to control the people by laws and punishments.
Meng Tian, a reputable general and a supporter of Qin Shi Huang's eldest son, Fusu, was stationed at the northern border, commanding more than 200,000 troops for the inconclusive campaign against the Xiongnu.
The fake decree forced Fusu to commit suicide and stripped Meng Tian of his command.
To preempt this, he launched a coup and assassinated Qin Er Shi, and then installed Ziying, Fusu's son, as the new emperor.
One chengyu (Chinese idiomatic expression) derived from an incident involving Zhao Gao is "point at a deer and call it a horse" (指鹿為馬; zhǐlù-wéimǎ) or "calling a deer a horse", figuratively meaning "deliberate peddling of a falsehood".
[6] The Records of the Grand Historian records that Zhao Gao, in an attempt to control the Qin government, devised a loyalty test for court officials using a deer and horse: Zhao Gao was contemplating treason but was afraid the other officials would not heed his commands, so he decided to test them first.
In fact, Zhao Gao killed all the sons and daughters of Qin Shi Huang, including the Second Emperor, Huhai.
[citation needed] The historian Li Kaiyuan (李開元) believes Zhao Gao was not a eunuch at all.
In addition, historians prior to Eastern Han did not explicitly describe Zhao Gao as a eunuch.
Archaeological findings of statues from the Qin dynasty also portrayed imperial coachmen, who may have been modelled after Zhao Gao, as bearded non-eunuchs.