In order to resist Zhang Lu, Liu Zhang invited Liu Bei to enter the river. Liu Bei found out the situation in Yizhou after staying at Yemengguan for a year, and the strategy of capturing Xichuan was put on the agenda. The military commander Pang Tong proposed to Liu Bei three strategies: the upper strategy was to raid Chengdu with elite troops and directly capture Yizhou; the central strategy was to seek an opportunity to capture Baishui Pass defended by Yang Huai and Gao Pei, and then take the road to kill Chengdu; the next strategy was to retreat to the White Emperor City and gather the Jingzhou army to gradually encroach on the land of Yizhou. In the end, Liu Bei adopted the middle strategy, so why didn't he adopt the upper strategy?
Liu Bei's reason was that the strategy was too hurried, in fact, he said this to a large extent to take care of Pang Tong's face. In Liu Bei's view, Pang Tong's superior strategy was not reliable at all, even the way to die. Why? From Yemeng Pass to Chengdu, there is only one avenue from Baishui Pass, and there is also Liu Zhang's troops guarding each pass along the way. Therefore, if you want to sneak into Chengdu, the avenue is impossible, so you can only take the trail.
The road in central Shu has always been difficult to navigate, and Li Bai once said that "the Shu Road is difficult, it is difficult to go to the Qingtian", and sneaking up on Chengdu from the small road is bound to take a lot of time because the road is difficult to travel. In this way, it is difficult to ensure that it will not be detected, and once it is discovered by Liu Zhang's men, Liu Bei's elite army will fall into the danger of being attacked by the enemy in the abdomen and back, and if it is not done well, the entire army will be destroyed. Even if he was not noticed and successfully reached the city of Chengdu, it was not easy to capture Chengdu! Liu Yan's father and son have been operating here for decades, and Chengdu is not only fortified, but also has sufficient grain and grass. The Yizhou shi clan was very disgusted with Liu Bei, and as early as when Liu Zhang invited Liu Bei to enter Sichuan, Huang Quan, Li Hui, and Wang Lei and others desperately dissuaded them, and Wang Lei even gave advice to death, but unfortunately Liu Zhang did not listen at that time.
Liu Bei always regarded himself as benevolent and righteous, and at the beginning of entering Sichuan, he repeatedly stated that he would not seize Liu Zhang's inheritance. Now suddenly leading troops to sneak into Chengdu, didn't you punch yourself in the face? Such a rebellion is bound to lead to a very unfavorable moral situation. All over Chengdu will also share the same hatred and vow to resist to the death. If he could not capture Chengdu in a short period of time, Liu Bei would be very troublesome, and all his military supplies at Ye Mengguan were supplied by Liu Zhang. Now that the two of them are looking at each other, Liu Bei's logistics will be guaranteed, and if the soldiers can't even eat, how can this battle be fought?
Some people may say that there are two internal responses in Chengdu, Zhang Song and Fazheng, so that they can take Chengdu inside and outside. However, zhang song and fazheng are not of high status and both are civilian officials and have no military power, and the role they can play is really limited, and judging from Zhang Song's later performance, he is not a person who does big things. Therefore, judging from the above points, the possibility of success in the sneak attack on Chengdu is very small, but the probability of failure is very large, while Liu Bei cannot afford to lose, and once defeated, the entire army may be destroyed. Therefore, this superior policy proposed by Pang Tong is undoubtedly the way to take death in Liu Bei's view, but he is not convenient to say it directly, so he rejects it on the grounds that the above policy is too urgent, which not only avoids the risk but also saves Pang Tong's face.