Liu Bei's takeover of Yi Province

Liu Bei's takeover of Yi Province was a military campaign by the warlord Liu Bei in taking control of Yi Province (covering present-day Sichuan and Chongqing) from its Governor, Liu Zhang. The campaign took place between 212 and 215 in the late Eastern Han Dynasty. It concluded with victory for Liu Bei and his successful takeover of the province from Liu Zhang. Yi Province would serve as the foundation of the state of Shu Han during the Three Kingdoms period.

Background
After the Battle of Red Cliffs, Sun Quan invited Liu Bei to take Yi Province with him, but the latter strongly rebutted the former, saying: "if you're going to conquer the land of Shu, I will loosen my hair and become a hermit in the deep hills. Earth under Heaven can hear my promise, and I'll live up to my words!" Believing Liu Bei, Sun Quan aborted his plan; however, Liu was actually trying to take Yi Province for himself and negotiated Yiling County and Nan Commandery from Sun. In 211, Liu Zhang, Governor of Yi Province, heard that Cao Cao was planning to attack Zhang Lu in Hanzhong. As Hanzhong was a strategic location and the "gateway" into Yi Province, Liu Zhang sent Fa Zheng to form an alliance with Liu Bei after persuasion from Zhang Song. Liu Bei then led his men to Yi Province under the pretense of helping Liu Zhang conquer Hanzhong.

Takeover of Jiameng
Liu Bei led an expedition force into Sichuan after leaving behind Zhuge Liang, Guan Yu, Zhang Fei and Zhao Yun to guard Jing Province. Liu Zhang received Liu Bei warmly and provided him with more troops under his command as well as abundant provisions and equipment. Liu Bei headed to Jiameng Pass (southwest of present-day Guangyuan, Sichuan) at the border between Liu Zhang and Zhang Lu's territories. Instead of engaging Zhang Lu, Liu Bei halted his advance and focused on building up connections and gaining influence around the area in preparation for his takeover of Yi Province.

In 212, Pang Tong outlined three plans for Liu Bei to choose from: The first was to advance swiftly to seize Chengdu from Liu Zhang. The second was to take command of Liu Zhang's armies in the north and then move to capture Chengdu. The third one was to return to Baidicheng to await further action. Liu chose the second option and lied to Liu Zhang that he needed more troops to divert Cao Cao's attention away from the east (where Sun Quan was under attack), and requested for another 10,000 soldiers and additional provisions to aid in the defense of Jing Province. Liu Zhang gave him 40% of the troops and half of the others he asked for.

Zhang Su (張肅), Zhang Song's older brother, discovered his brother's secret communications with Liu Bei and reported the issue to Liu Zhang. Liu Zhang was furious and stunned when he heard that Zhang Song had been helping Liu Bei to plot against him - he had Zhang executed, and ordered his generals guarding the passes to Chengdu to keep secret his knowledge of Liu Bei's intention. Despite so, Liu Bei was informed by his spies planted around Liu Zhang, and before Liu Zhang's men could reach Yang Huai and Gao Pei (高沛), generals guarding Boshui Pass, Liu Bei summoned and killed them on the excuse that they were disrespectful towards him. Liu Bei then took over their troops and turned to attack Fucheng (涪城). On his way, Liu Bei's troops bypassed the city of Zitong, where the defenders closed the gates and resisted the invasion.

Bribery strategy
In the spring of 213, Liu Zhang sent Liu Gui (劉璝), Ling Bao (冷苞), Zhang Ren, Deng Xian (鄧賢), and other generals under Wu Yi (吳懿) to defend Mianzhu (綿竹). Despite being the most trusted vassal of Liu Zhang, Wu Yi soon changed allegiance, so Li Yan and Fei Guan (費觀) were sent to replace him, but they surrendered to Liu Bei as well. At the time, Liu Zhang's soldiers were not used to intense combat and were low on morale, and he did not dish out intimidating punishments to the families of those surrendered, so only a few generals were determined to fight the invaders. On the contrary, Liu Bei was promising to provide wealth and positions to those who would switch allegiance, so many generals simply welcomed him along his way until he reached the city of Luo (雒, today's Guanghan, northwest of Chengdu), where the ones who could not be bought by wealth nor power played their staunch defense.

Defense of Luo
The remnant force was now placed under command of Liu Zhang's son Liu Xun, and he retreated to Luo to join forces with Ling Bao. There, Liu Bei had the city surrounded, and his advisor Pang Tong personally led a major assault, but the defenders fought back with projectiles and Pang was killed by a stray arrow. Thus, the siege became a prolonged one, forcing Liu Bei to call forth reinforcements from Jing Province. Zhang Fei led an army from Jing Province to attack Jiangzhou (in present-day Chongqing), where he captured an enemy general, Yan Yan. Facing Zhang Fei's insults, Yan Yan condemned him for invading Yi Province. Yan Yan was originally ordered to be executed by the angry Zhang Fei, but his fearlessness of death impressed Zhang and his life was pardoned. Following the Dian River (垫江), Zhang Fei broke through the thin defense line guarded by an enemy major of Liu Zhang, and rendezvoused with Liu Bei. Zhao Yun and Zhuge Liang also arrived from another route. Zhang Ren attempted to broke the siege by leading his men onto the Wild Goose Bridge and engaged Liu Bei's forces, but was defeated and captured. His loyalty and bravery were well known, so Liu Bei ordered his army to force him into submission. However, Zhang Ren cried out his famous line: "A loyal subject will never serve two masters!" Liu Bei lamented on his determination and had him executed.

Fall of Chengdu
More than a year had passed and Luo finally fell, but Liu Zhang continued to hold on inside Chengdu. Ma Chao, a former Liang Province warlord and a vassal of Zhang Lu, was persuaded by Liu Bei to kill his comrade, Yang Bai (楊柏), and joined Liu. Upon seeing Ma Chao's army to the north of Chengdu, the citizens inside the city was terrified, but they still insisted on fighting a desperate war. However, Liu Zhang came out, and said to the public that the people had already fought for him for more than three years, and his heart was broken upon seeing the commoners dying on the field just for the sake of him. Thus, he opened the city gates and surrendered himself to Liu Bei; everyone inside the city wept for Liu Zhang's sacrifice. Liu Bei then succeeded Liu Zhang as Governor of Yi Province, and he conferred on the latter the seal and tassel of General Who Inspires Awe (奮威將軍) before expatriating him to Gong'an.

Liu Bei married Wu Yi's sister and attempted to solidify his control on the newly conquered domain. Most of Liu Bei's followers, new and old, were promoted to higher ranks; and a set of straight law code was applied to Yi Province, replacing the softer one set by Liu Zhang.

Aftermath
Upon hearing Liu Bei had taken Yi Province, Sun Quan sent envoys to ask him for the return of his interest in southern Jing Province, but Liu said: "Jing Province will be returned after I take Liang Province." Sun Quan was furious when his envoy reported Liu Bei's words, and he sent Lü Meng and Ling Tong with another four generals to take over southern Jing province. Three commanderies were soon conquered, and Liu Bei personally went to Gong'an in an attempt to retake them, but he finally came to a border treaty with Sun Quan when he heard Cao Cao was planning to attack Hanzhong.

Liu Bei forces

 * Liu Bei
 * Pang Tong
 * Liu Feng
 * Huang Zhong
 * Wei Yan
 * Huo Jun
 * Zhang Fei
 * Zhuge Liang
 * Zhao Yun
 * Ma Chao, defected over from Zhang Lu's side to Liu Bei

Liu Zhang forces

 * Liu Zhang
 * Zhang Ren, captured and executed
 * Zhuo Ying (卓膺)
 * Wu Lan (吳蘭)
 * Lei Tong
 * Liu Xun
 * Yang Huai, executed by Liu Bei
 * Gao Pei (高沛), executed by Liu Bei
 * Liu Gui (劉璝)
 * Ling Bao (冷苞)
 * Deng Xian (鄧賢)
 * Wu Yi (吳懿)
 * Li Yan
 * Fei Guan (費觀)
 * Zhang Yi (張翼)
 * Yan Yan, captured and surrendered
 * Huang Quan

Modern references
The campaign is featured as one of the playable stages in Koei's video game series Dynasty Warriors. In the game, all the battles in the campaign were aptly summed up in one single battle, called the "Battle of Chengdu", although technically, there was no battle fought at Chengdu at all in the campaign. In Dynasty Warriors 3 and Dynasty Warriors 4, Liu Zhang's surrender is optional and often a special requirement for certain unlockable items. The concept was removed in Dynasty Warriors 5 and Liu Zhang surrenders immediately after his defeat. In Dynasty Warriors 6, the battle is renamed to "Pacification of Chengdu" and the geographical design of the stage has changed but the events remain almost the same. In Dynasty Warriors 7, the campaign is split into two battles with the Battle of Luo Castle and battle of Chengdu. Battle of Luo Castle has Liu Xun as commander of Liu Zhang's forces and Pang Tong as commander of Liu Bei's forces. The battle serves as Pang's only appearance in story mode. The Battle of Chengdu follows Lou Castle with Zhuge Liang as commander after Pang's death.