From Baidu:

ZHANG Yi (?) - 309 BC), a native of Zhangyi Village, Anyi (now Wanrong, Shanxi), was a descendant of Wei nobles, and a famous columnist, diplomat and strategist during the Warring States Period. Zhang Yi pioneered the diplomatic strategy of Lianheng and lobbied to enter Qin. King Qin Hui named Zhang Yi as the prime minister, and later Zhang Yi sent an envoy to lobby the vassal states to break the "vertical" with "horizontal", so that all countries have changed from joining forces to resist Qin to even horizontal and pro-Qin. Zhang Yi was also named Wu Xinjun by the King of Qin. After the death of King Qin Hui, because the enthroned King Wu of Qin did not like Zhang Yi when he was the crown prince, Zhang Yi fled to Wei and served as the minister of Wei, and died a year later.