Qin's wars of unification

Qin's wars of unification were a series of military campaigns conducted in the late 3rd century BC by the Qin state against the other six major states (Han, Zhao, Yan, Wei, Chu, Qi) in the territories that later became China. By the end of the wars in 221 BC, Qin had unified most of these states and also conquered some lands south of the Yangtze River. The territories annexed by the Qin became the homeland of the Chinese nation and formed the basis of the Qin Dynasty.

Background


Over the course of the Warring States period, the Qin state had evolved to become the most powerful of the seven major states in China. In 238 BC, Ying Zheng came to the throne of Qin after eliminating his political rivals, the chancellor Lü Buwei and the Marquis of Changxin, Lao Ai (嫪毐). With help from Li Si (李斯), Wei Liao (尉繚) and others, Ying Zheng formulated a plan for conquering the other six major states and unifying China. The key steps in the plan were: ally with Yan and Qi, hold down Wei and Chu, conquer Han and Zhao; using the strategy of "ally with distant states and attack nearby ones" and focus on annexing each state individually.

Conquest of Han
Han was the weakest of the Seven Warring States and had already been subject to many previous attacks by Qin, which caused it to be drastically weakened further. In 230 BC, the Qin army led by Interior Minister Teng (內史騰) moved south, crossed the Yellow River and conquered Zheng (鄭; present-day Xinzheng, Zhengzhou, Henan), the capital of Han, within one year. King An of Han surrendered and Han was annexed by Qin. The territory of Han was reorganised as Yingchuan commandery (潁川郡) of the Qin empire, with its capital at Yangzhai (陽翟; present-day Yuzhou, Xuchang, Henan).

Conquest of Zhao
In 236 BC, Qin used the opportunity to send two separate forces to attack Zhao, while Zhao was invading Yan. The Qin army led by Wang Jian conquered the Zhao territories of Eyu (閼與; present-day Heshun County, Jinzhong, Shanxi), Liaoyang (撩陽; present-day Zuoquan County, Jinzhong, Shanxi), while a separate Qin force under the command of Huan Yi (桓齮) and Yang Duanhe (楊端和) captured Ye (鄴; present-day Ci County, Handan, Hebei) and Anyang (安陽; present-day Anyang County, Anyang, Henan). Zhao lost nine cities and its military strength decreased.

Two years later, Qin planned to attack Han, but feared that Zhao might render support to Han, so it sent an army under Huan Yi's command to attack Zhao's Pingyang (平陽; southeast of present-day Ci County, Handan, Hebei) and Wucheng (武城; southwest of present-day Ci County, Handan, Hebei). More than 100,000 casualties were sustained and the Zhao army was defeated, with its commander Hu Zhe (扈輒) being killed in action. In 233 BC, Huan Yi's force crossed Mount Taihang and conquered the Zhao territories of Chili (赤麗) and Yi'an (宜安), both located southeast of present-day Shijiazhuang, Hebei.

In 232 BC, the Qin forces split into two groups to attack Fanwu (番吾; present-day Lingshou County, Handan, Hebei) and Langmeng (狼孟; present-day Yangqu County, Taiyuan, Shanxi), but were defeated by the Zhao army led by Li Mu. Huan Yi fled to the Yan state to escape punishment for his defeat. However, the Zhao forces also sustained heavy losses and could only retreat to defend their capital, Handan.

In the following two years, Zhao was struck by an earthquake and suffered from a severe famine. In 229 BC, Qin took advantage of the situation when Zhao was suffering from natural disasters to launch a two-pincer attack from north and south on Handan, capital of Zhao. Three Qin armies embarked from Shangdi (上地; in present-day northern Shaanxi), Jingxing (井陉; present-day Jingxing County, Shijiazhuang, Hebei) and Henei (河內; present-day Xinxiang, Henan), respectively led by Wang Jian, Jiang Lei (羌瘣) and Yang Duanhe, to coordinate the attacks on Handan. Li Mu and Sima Shang (司馬尚) were put in command of the Zhao army and Li Mu ordered his troops to build defensive structures and avoid direct confrontation with the Qin invaders. The Qin forces were unable to advance further and both sides reached a stalemate.

The Qin state bribed Guo Kai (郭開), a minister in Zhao, to sow discord between King Qian of Zhao (趙王遷) and Li Mu. The king doubted Li Mu's loyalty and ordered Li to hand over his command of the Zhao army to his deputies Zhao Cong (趙蔥) and Yan Ju (顏聚), but Li refused and the king's suspicions increased. The king sent his men to take Li Mu by surprise and capture him and Li was killed later.

In 228 BC, after learning that Li Mu had been replaced by his incompetent deputies, the Qin forces attacked and defeated the Zhao army, capturing Dongyang (東陽; east of Mount Taihang), while Zhao Cong was killed in action and Yan Ju escaped after his defeat. Seven months later, the Qin forces conquered Handan and captured King Qian, bringing an end to the Zhao state's existence.

King Qian's elder brother Prince Jia escaped to Dai (代; present-day Yu County, Zhangjiakou, Hebei) with remnant forces and proclaimed himself "King of Dai". In 222 BC, Dai was conquered along with Yan by the Qin army, led by Wang Ben (王賁), and Zhao Jia was captured.

Conquest of Yan
In 228 BC, after the fall of Zhao, the Qin army led by Wang Jian stationed in Zhongshan and prepared for an offensive on Yan. The Yan minister Ju Wu (鞠武) proposed to King Xi to form alliances with Dai, Qi and Chu, and improve relations with the Xiongnu in the north, in order to counter the Qin invaders. However, Crown Prince Dan thought that the strategy of forming alliances was unlikely to succeed, so he sent Jing Ke to assassinate Ying Zheng, the king of Qin. Jing Ke went to Qin by pretending to be an envoy, bringing with him a map of Dukang and the severed head of Fan Wuji, a turncoat Qin general. The assassination attempt failed and Jing Ke was killed.

In 226 BC, using the assassination attempt as an excuse, Ying Zheng ordered Wang Jian to lead an army to attack Yan, with Meng Wu (蒙武) serving as Wang Jian's deputy. The Qin forces defeated the Yan army and Yan's reinforcements from Dai in a battle on the eastern bank of the Yi River (易水), and captured Ji (薊; present-day Beijing), the capital of Yan. King Xi of Yan and his son, Crown Prince Dan, led their remaining forces on a retreat to Liaodong (present-day Liaoning). The Qin army led by Li Xin (李信) pursued the retreating Yan forces to the Yan River (衍水; present-day Hun River, Liaoning) and emerged victorious in the battle, destroying the bulk of the Yan military. King Xi had Crown Prince Dan killed later and sent his son's severed head to Qin, as a token of peace. Qin accepted the offer and did not attack Yan for the next three years.

In 222 BC, the Qin army led by Wang Ben (王賁) invaded Liaodong and destroyed the remnant forces of Yan and captured King Xi, annexing the Yan state completely. The former territories of Yan were divided into the Yuyang (漁陽), Beiping (北平), Liaoxi (遼西) and Liaodong (遼東) commanderies of the Qin Empire.

Conquest of Wei
In 225 BC, the 600,000 strong Qin army led by Wang Ben (王賁) conquered more than ten cities on the northern border of the Chu state, as a precautionary move to guard the flank from possible attacks from Chu while Qin was invading Wei. Wang Ben then led his forces northward to attack and besiege Daliang (大梁; northwest of present-day Kaifeng, Henan), the capital of Wei. As Daliang was situated at the concourse of the Sui and Ying rivers and the Hong Canal (鴻溝), its geographical location placed it in a defensive position that is hard for Qin to attack. Besides, the moat around Daliang was very wide and all the five gates of the city had drawbridges, making it even more difficult for Qin forces to penetrate the city. The Wei troops used the opportunity to strengthen their fortifications and defences.

Wang Ben came up with the idea of directing the waters from the Yellow River and the Hong Canal to flood Daliang and succeeded after besieging Daliang for three months. Daliang was heavily flooded and the Wei forces sustained more than 100,000 casualties, including civilians. King Jia of Wei (魏王假) surrendered and the Wei state was annexed by Qin. Qin established the commanderies of Dang (碭) and Sishui (泗水) in the conquered Wei territories.

Conquest of Chu
In 224 BC, Ying Zheng called for a meeting with his subjects to discuss his plans for the invasion of Chu. Wang Jian said that the invasion force needed to be at least 600,000 strong, while Li Xin (李信) thought that less than 200,000 men would be sufficient. Ying Zheng dismissed Wang Jian's idea and ordered Li Xin and Meng Wu (蒙武) to lead the army to attack Chu, while Wang Jian retired, claiming that he was ill.

The Qin armies scored initial victories as Li Xin's army conquered Pingyu (平輿; north of present-day Pingyu County, Zhumadian, Henan) and Meng Wu's force captured Qinqiu (寢丘; present-day Linquan County, Fuyang, Anhui). After conquering Yan (鄢; present-day Yanling County, Xuchang, Henan), Li Xin led his army westwards to rendezvous with Meng Wu at Chengfu (城父; east of present-day Baofeng County, Pingdingshan, Henan). The Chu army, led by Xiang Yan (項燕), had avoided using its main force to resist the Qin invaders while waiting for an opportunity to launch a counterattack.

During the time, Lord Chang Ping's incited a rebellion from a castle previously conquered by Li Xin,and was preparing for a surprise attack against Li Xin forces as well.

The Chu forces followed Li Xin's army secretly at high speed for three days and three nights, before launching a surprise attack. Chang Ping's force follow suite,from behind, and they together destroyed most of Li Xin forces and ending his campaign.

Upon learning of Li Xin's defeat, Ying Zheng visited Wang Jian in person and invited him back, putting Wang in command of a 600,000 strong army as he had requested earlier, with Meng Wu serving as Wang's deputy. As Wang Jian was aware that Ying Zheng might doubt his loyalty because he wielded too much military power, he frequently sent messengers back to the king, requesting for rewards for his family in order to reduce the king's suspicions.

In 224 BC, Wang Jian's army passed through the south of Chen (陳; present-day Huaiyang County, Zhoukou, Henan) and made camp at Pingyu. The Chu armies, led by Xiang Yan, used their full strength to launch an offensive on the Qin camp but failed. Wang Jian ordered his troops to defend their positions firmly and avoid advancing further into Chu territory. After failing to lure the Qin army to attack, Xiang Yan ordered a retreat and Wang Jian seized the opportunity to launch a surprise counterattack. The Qin forces pursued the retreating Chu forces to Qinan (蕲南; northwest of present-day Qichun County, Huanggang, Hubei), where Xiang Yan was killed in action in the ensuing battle.

In 223 BC, Qin launched another attack on Chu and captured Shouchun (壽春; present-day Shou County, Lu'an, Anhui), the capital of Chu. Fuchu, the king of Chu, was captured and the Chu state was annexed by Qin. The following year, Wang Jian and Meng Wu led the Qin army to attack the Wuyue region (covering present-day Zhejiang and Jiangsu) inhabited by the Baiyue, and captured the descendants of the royal family of Yue. The conquered Wuyue territories became the Kuaiji commandery (會稽郡) of the Qin Empire.

Conquest of Qi
In 224 BC, King Jian (齊王建) succeeded to the throne of Qi and his mother, the queen dowager, assisted him in managing state affairs. The Qin state bribed Hou Sheng (後勝), the Qi chancellor, to dissuade the king of Qi from assisting the other states in countering invaders from Qin. In 221 BC, Qi was the only remaining state in China that had not been annexed by Qin. Qi only realised then that Qin posed a great threat and hurriedly mobilised its armies to the western frontier to defend against an invasion by Qin, even though its military was not well equipped and morale was low.

In the same year, Ying Zheng used Qi's rejection of a meeting with Qin's envoy as an excuse to order Wang Ben (王賁) to lead an army to attack Qi. Wang Ben's force avoided direct confrontation with the Qi armies on the western border of Qi, and advanced into the heartland of Qi via a southern detour from Yan. The Qin forces met with little resistance as they passed through Qi territories and eventually arrived at Linzi (臨淄; north of present-day Zibo, Shandong), the capital of Qi. The Qi forces were caught by surprise and King Jian surrendered to Qin without a fight after persuasion from Hou Sheng. The annexed territories of Qi became the Qi (齊) and Langya (琅邪) commanderies of the Qin Empire.

Aftermath
In 221 BC, after the conquest of Qi, Ying Zheng proclaimed himself "Qin Shi Huang" (秦始皇; "First Emperor of Qin") and founded the Qin Dynasty. The Qin Empire was divided into 36 prefectures, with Xianyang as the capital. Qin Shi Huang created a centralised state and empire that would become the bedrock of future Chinese dynasties. Although the Qin Dynasty lasted for 16 years only, its influence and impact on Chinese history lasted for centuries to come.

In 209 BC, during the reign of Qin Er Shi (Qin Shi Huang's son and successor), Chen Sheng and Wu Guang started an uprising to overthrow the Qin Dynasty due to the Qin government's brutal and oppressive policies. Although the revolt was crushed by imperial forces, several other rebellions also started consecutively all over China over the next three years. The last Qin ruler, Ziying, surrendered to a rebel leader Liu Bang in 206 BC, bringing an end to the Qin Dynasty. Several of the rebel forces claimed to be restoring the former states that were annexed by Qin and numerous pretenders to the thrones of the former states emerged. The most prominent one, Xiang Yu, a pretender to the throne of Chu, declared himself "Hegemon-King of Western Chu", and sacked the Qin capital Xianyang after it fell in 206 BC.