Zhang Yi (張儀), whose date of birth was unknown, died in the first year (310 B.C.) or the second year (309 B.C.) of King Wu of Qin Dynasty. As an aristocratic descendant of State Wei, he learned vertical and horizontal (Zong and Heng) arguing tactic and became a famous politician, diplomatist, and strategist in Warring States Period.

During Warring States Period, the vassal states had frequent separatist wars, vying for supremacy. They adopted the strategy of “opposite theories of vertical and horizontal alliance of states with the state of Qin as pivot (He Zong Lian Heng)”. “He Zong” meant unifying weak vassal states to prevent the merger of powerful states. “Lian Heng” meant following a powerful state to invade weak states, in order to annex their territory. Zhang Yi, as an outstanding political strategist, had a great influence on the merger of vassal states and the change of war situation.

In the 9^th year of Duke Huiwen of Qin State (329 B.C.), Zhang Yi went to Qin State from Zhao State. With his exceptional intelligence, he was appointed as alien minister by King Hui of Qin State to plan and prepare invading other states. The next year, following the example of bureaucracies of San Jin, Qin State began to set up the position of prime minister, which was called Xiang Bang or Xiang Guo. Zhang Yi was the first Xiang Guo, ranking the head of all officials. He involved in important affairs of army and government as well as diplomatic activities. From then on, he started his career of politics, diplomacy and military.

Being Xiang Guo, Zhang Yi actively planned for Qin State. Using Lian Heng tactic, he forced the princes of Han State and Wei State to come to Qin State to worship; and seized Pu Yang of Wei State (now Xixian County, Shanxi Province) with Childe Hua. Later, he persuaded King Hui of Wei State to consecrate 15 counties of Shang Jun, including Shao Liang (now the south of Han Cheng, Shaanxi Province) to Qin State, without sacrificing a solider. In the 13^th year of Duke Huiwen of Qin State (325 B.C.), Zhang Yi led the army to conquer Shan County of Wei State (now Shanzhou District, Henan Province). In this way, the natural barrier of the Yellow River was occupied by Qin. With the growing power of Qin State, Zhang Yi assisted Duke Huiwen of Qin State to become a king in 325 B.C.

In the second year of King Huiwen of Qin State (323 B.C.), in order to confront He Zong policy of King Hui of Wei State and invade Wei State, Zhang Yi used Lian Heng tactic and met the ministers of Qi State and Chu State in Nie Sang (now southwest of Pei county, Jiangsu Province) to eliminate the worries of Qin State’s eastward invasion. When Zhang Yi came back to Qin State, he was relieved from the post of Xiang Guo. In 323 B.C., Wei State failed to ally with Qi State and Chu State and had to appoint Zhang Yi as the minister, trying to invade Qi State and Chu State with Qin State and Han State. In fact, the ultimate goal of Zhang Yi was to make Wei State attach itself to Qin State. Under the threat of Lian Heng policy, in 319 B.C., Gong Sunyan from Wei State was appointed as the prime minister of Wei State with the support of Qi State, Chu State, Han State, Zhao State, and Yan State; therefore, Zhang Yi was expelled to Qin State. In 317 B.C., Zhang Yi became Xiang Guo of Qin State for the second time. In 317 B.C., King Hui of Qin State accepted the advice of Sima Cuo and sent Zhang Yi and Sima Cuo to invade Shu State. They won the victory and later annihilated the states of Ba and Qie. In this way, Qin occupies Shu State, the land of abundance, as strengthened rear area, providing advantages for Qin State’s economic development and military war.

In the 12^th year (313 B.C.), King Hui of Qin State intended to invade Qi State. In fear of the alliance of Qi State and Chu State, he sent Zhang Yi to persuade King Huai of Chu State. Zhang Yi said: “If Chu State can break off with Qi State, Qin State would like to give away six hundred miles of Shang Yu to Chu State”. King Huai of Chu State believed in his words and cut off relation with Qi State. Then King Huai sent envoy to Qin State, but Zhang Yi told him: “We had an appointment of six miles instead of six hundred miles”. King Huai of Chu State was so mad that he started the war against Qin State. In the 13^th year (312 B.C.), the army of Chu State was defeated in Dan Yang (now the north of Dan Shui, the west of Henan Province). Qin State captured more than 70 generals of Chu State and six hundred miles of Hanzhong. From then on, Bashu area and Hanzhong were connected together, removing the threat of Chu State and expanded the territory of Qin State. According to Biographies of Zhang Yi in Historical Records, “There are many people with adaptability in tactics in Sanjin, so those who could make Qin State become more powerful must be from Sanjin”. There was no doubt that Zhang Yi was the most outstanding one.

In the 14^th year of King Hui of Qin State (311 B.C.), Zhang Yi went to lobby Chu State, Han State, Qi State, Zhao State, and Yan State to be under the leadership of Qin State. In the same year, Zhang Yi received a reward of five counties and was awarded the title of Wu Xin Jun.

On the basis of Shang Yang’s Reforms, combining Lian Heng tactic and the policy of planting and war together, Zhang Yi maneuvered among various vassal states with eloquence and strategy. He made many achievements and became a decisive figure in politics, diplomacy and military affairs of Qin State. Under the dangerous environment full of changes, relying on diplomacy and Lian Heng tactic, Zhang Yi made Qin State become more powerful and had a great deterrent effect on other vassal states. Jing Chun, disciple of Mencius, complimented him: “Gong Sunyan and Zhang Yi are real men. When they are angry, the other vassal states are so afraid; when they stay at home, the world live in peace.” Zhang Yi helped Qin State capture Sanchuan, Ba, Shu, Shangjun and Hanzhong, which played a positive role in the hegemony and future unification of Qin State. In the 14^th year of (311 B.C.), King Hui of Qin State died and his son King Wu of Qin State ascended the throne. Zhang Yi was not satisfied with King Wu of Qin State, so he left Qin State for Wei State. Later, he died in Wei State.