First of all, it is because Liu Bei is headstrong, which is the fundamental reason for the failure of the Yiling War.

Then he made a mistake in the specific battle plan. At that time, Liu Bei led an army of 750,000, while Sun Wu only resisted with an army of 100,000, even weak against strong. Liu Bei was eager for revenge, relying on a large number of soldiers, and adopted the method of urgent battle, and won the first victory. Sun Wu was afraid, but Liu Bei refused, so Wu must be destroyed. As a result, Sun Quan was forced to use a young Confucian general, Lu Xun, as the commander in chief. This man is very young, and many people in Dongwu look down on him, but he is smart and resourceful. His tactics are: avoid its spirit, don't insist, and wait for work. As a result, the Shu army, which was originally in full swing, was dragged "exhausted", and the weather was hot and it was difficult to drink water. Finally, Liu Bei had to order a camp in the dense forest of 700 miles. Zhuge Liang saw the company camp map sent back by Liu Bei and immediately complained: "The luck of the Han Dynasty has been used up!" As a result, the Shu army was set on fire by Wu Jun, who was earlier and earlier, and burned 700 Li Lian's battalion, which was a fiasco.