In 236 BC, Wang Jian commanded the Qin army which attacked Zhao and captured nine cities. This action represented the start of King of Qin, Ying Zheng's wars of unification. The Kingdom of Zhao ceased to exist in 228 BC after Wang Jian used spies in the Zhao court to have Zhao's leading general Li Mu replaced and then he captured Zhao's king. According to the Grand Historian, after Jing Ke failed in his attempt to assassinate emperor Qin Shi Huang, the Kingdom of Yan where Jing Ke was a retainer, was conquered by General Wang Jian in 226 BC. A year later, Wang Jian's son Wang Ben conquered the Kingdom of Wei.
Conquest of Chu, 225–223 BC
In 225 BC, only two kingdoms remained independent: Chu and Qi. Chu had recovered significantly enough to mount serious resistance after their disastrous defeats to Qin in 278 BC and losing their centuries-old capital of Ying. Despite its territorial size, resources and manpower, Chu's fatal flaw was its largely corrupt government that mostly overturned the legalistic-style reforms of Wu Qi from a century and a half earlier, when Wu Qi transformed Chu into the most powerful state with an area of almost half of all the other states combined. Wu Qi was from the same state as Shang Yang, whose legalistic reforms turned Qin into an invincible war machine. The King of Qin, Ying Zheng, decided to finally defeat the remnants of the Chu state located in Huaiyang. According to Shiji's chapter on the great generals of the Warring States, Ying Zheng had first requested his general Wang Jian to lead the invasion, and further inquired as to the military strength needed for the siege. Wang Jian stated that he needed a force of 600,000 men for the invasion. However, when the same question was posed to Li Xin, he requested only 200,000 men. Ying Zheng accepted Li Xin's advice. Wang Jian retired, claiming ill health. The first Qin invasion was a disaster when the 200,000 Qin troops were defeated by 500,000 Chu troops in the unfamiliar territory of Huaiyang. Ying Zheng recalled Wang Jian, who finally agreed to lead the second invasion force after being allocated the force of 600,000 men that he had earlier requested. In 224 BC, Wang Jian began the second invasion by Qin forces of Chu. Chu's morale had greatly increased after their success the previous year. The Chu forces were content to wait and defend their territory. Wang Jian tricked the Chu army by appearing inactive within his fortifications while secretly training his troops to fight in Chu territory. After a year, Chu decided to disband most of their army due to the lack of action. Wang Jian then invaded and overran Huaiyang and the remaining Chu forces. Xiang Yan, the Chu general, managed to resist and inflict bloody losses on Wang Jian until King Fuchu of Chu was killed by Wang Jian's second in command, Meng Wu, father ofMeng Tian. Chu was finally conquered by Qin in 223 BC. At their peak, the armies of Chu and Qin combined numbered over 1,000,000 troops, more than the massive campaign at Changping between Qin and Zhao 35 years earlier. The excavated personal letters of two Qin regular soldiers, Hei Fu and Jin, records a protracted campaign in Huaiyang under general Wang Jian. Both soldiers wrote letters requesting supplies and money from home to sustain the long campaign.
Cultural reference
In Manga and Anime Kingdom where he is known as Ousen, he was described as a silent tactician. His army can construct defenses quickly, can think while scouting the terrain and decide who is who.
