In 221, the Shu Han Emperor Liu Bei personally led a large army to conquer Eastern Wu, and as a result, he was defeated by the Wu general Lu Xun at the Battle of Yiling the following year, suffering heavy losses. Liu Bei said indignantly, "I am humiliated by Sun, am I not a heavenly evil!" Looking at Liu Bei again, the reason why he was defeated was due to providence. However, people unanimously believe that Liu Bei was defeated because he made a very serious military mistake, that is, seven hundred miles of company camp!
First, will Liu Bei use troops?
During the battle between Wu and Shu, Emperor Cao Pi of Wei saw Liu Bei's deployment and said to his courtiers: "If you don't know how to prepare soldiers, how can there be a seven-hundred-mile battalion that can resist the enemy?" 'The soldiers are birds of the enemy', this soldier is also jealous. In Cao Pi's view, Liu Bei did not understand the art of war at all, how could he camp for seven hundred miles, so that he certainly could not resist the enemy. Later people also agreed with Cao Pi, believing that Liu Bei would not fight at all.
But don't forget how Cao Pi's father, Cao Cao, evaluated Liu Bei in those years, "The heroes of the world are only the king and Cao'er." How could Liu Bei, who did not even look down on Cao Cao, not fight a war? Although Liu Bei lost more than he won in the course of his conquest, most of them were defeated by Cao Cao. In the Battle of Bowangpo, Liu Bei made a small plan to break Xiahou Yuan and Yu Ban; in the Battle of Hanzhong, Liu Bei first killed Xiahou Yuan and forced Cao Cao to withdraw his troops, which shows that Liu Bei did not understand the art of war and could not use troops.
Second, Liu Bei's military deployment
Since Liu Bei would use troops, how did he conduct this battle against Wu? After the outbreak of war, Wu Ban and Chen Shi led the water army of Shui Han to the vicinity of Yiling, and then Liu Beicai led a large army to arrive. At this time, the Shu army had penetrated hundreds of miles into the territory of the State of Wu, but the Wu army could not hold out. Before and after this, Liu Bei made some arrangements for the Shu army. First, the general Huang Quan was sent to lead a part of the army to garrison the north bank of the Yangtze River to prevent Cao Wei's attack.
Second, Liu Bei ordered Wu Ban and Chen Shi's water army to abandon the boat and land on the shore. Finally, Liu Bei set up a company camp and set up dozens of large camps within hundreds of miles along the Wuxia and Jianping to Yiling lines. In addition, Liu Bei also sent Ma Liang to Wuling to "give the Five Streams barbarians with gold and give them official titles" and let them respond with troops. Prior to this, Huang Quan said that "the subject please be a pioneer to be a pawn, and His Majesty should be the back town", but Liu Bei did not agree. So, why did Liu Bei do this, especially for seven hundred miles of camp?
Third, Liu Bei's helpless choice
Liu Beifa Wu faced many difficulties, the first of which was the problem of the water army. Due to the rapid flow of water in the Three Gorges area, basically there is no retreat, and the water army is the strength of Eastern Wu, so Liu Bei simply ordered the water army to abandon the ship and land. The second issue is logistics. Due to poor transportation, it was very difficult to transport grain from Shudi to the front line. Once the logistical supply was cut off, then the Shu Han army would collapse without a fight. Since Liu Bei gave up the water army, it was possible for Eastern Wu to use the Yangtze River to cut off the rear road of the Shu army.
If Huang Quan could not resist the intervention of Cao Wei's army, then the Wei army's direct attack on the back of the Shu army would also make the whole army passive. Another reason is also very important, Liu Bei's army is located in a mountainous area, the road is narrow, is not conducive to the full development of large troops. Since the two sides were in a confrontation, another advantage of the seven hundred miles of camp was to reduce the difficulty of transporting grain and grass. Probably for the above reasons, Liu Beicai camped seven hundred miles, but any decision could not be perfect, there would always be flaws.
References: 1. Chronicle of the Three Kingdoms; 2. Zizhi Tongjian