During the time of the Southern and Northern Dynasties, Zhang Sun Sheng, a wise sharp-shooting military attache from the Northern State, was sent on a mission: to escort the princess to the Turkic Clan's territory in the northwest to be married. The King of the Turkics appreciated Zhang Sun Sheng's shooting ability and kept him to go hunting with him. While on the hunt, they saw two big eagles in the sky fighting over a piece of meat, so the king asked him to shoot the eagles. Unexpectedly, he shot both eagles at the same time. So now people usually use the idiom to describe a situation where one action can accomplish two goals.