King Zhaoxiang of Qin or King Zhao of Qin (秦昭襄王 or 秦昭王) (324–251 BC) was the son of King Huiwen

Huiwen of Qin

King Huiwen of Qin , also known as Lord Huiwen of Qin or King Hui of Qin , personal name Ying Si , was the ruler of the Qin state from 338 BC to 311 BC during the Warring States Period of Chinese history.-Early life:...

 and younger brother of King Wu. After the death of Wu in 306 BC, Zhao contended for the crown of Qin with his younger brother. With the support of King Wuling of Zhao

King Wuling of Zhao

King Wuling of Zhao reigned in the State of Zhao during the Warring States Period of Chinese history...

, Zhao finally ascended the throne. During King Zhao's reign, the famous Qin general Bai Qi captured the 400 year old Chu capital of Ying in 278 BC. In 260 BC, King Zhao won the vital Battle of Changping

Battle of Changping

The Battle of Changping was a military campaign that took place during the Warring States Period in China. It concluded in 260 BC with a decisive victory by the State of Qin over the State of Zhao, and ultimately allowed Qin to conquer and unify China decades later...

 against the State of Zhao when General Bai Qi encircled the Zhao army and forced its surrender. He decided to massacre all 400,000 of the Zhao survivors.

Under King Zhao, Qin captured territory of the Yiqu (義渠) semipastoral people, acquiring the later commanderies of Longxi (陇西/隴西), Beidi (北地), and Shang (上), and build “long walls” for protection against the Hu

Wu Hu

Wu Hu was a Chinese term for the northern non-Chinese nomadic tribes which caused the Wu Hu uprising, and established the Sixteen Kingdoms from 304 to 439 AD.-Definition:...

(胡), northwestern nomadic people.