First, cruel abuse and loss of public support. When the Chu army arrived in Xin 'an, they attacked Qin Jun, which had been captured by Chu, and buried 200,000 people alive. They are actually children of Qin people wearing military uniforms. Xiang Yu also took away the treasures and goods of Qin maids; The fire in Xianyang Palace burned for three months. If we make a comeback, wouldn't the Qin people fight to the death? You burned not only the great material wealth created by the people of Qin-the palace, but also a lot of spiritual wealth such as China's ancient books and picture books. But Liu Bang, although the rogue proletarians still hate Confucian scholars and drool over palaces and beautiful women, still adopted the opinions of Xiao He, and Qiu did not commit any crime, which won the hearts of the people.

Second, headstrong, not good at employing people. There are many talented people around Liu Bang: Xiao He, Cao Can, Han Xin, Chen Ping, Peng Yue, Lu Jia, Zhou Bo ... Who else besides Yu Ji? War does not rely on strength to fight alone, it needs the highest collective wisdom and organizational ability to mobilize soldiers. Rejuvenating the country with talents is a law with strong vitality and a tried-and-true truth. The success of Liu Han Dynasty in seizing and consolidating political power is the best practical test of this truth. Liu Bang put it well: "I am not as good as Sean in making suggestions and winning thousands of miles;" I am not as good as Xiao He in governing the country, appeasing the people and raising the salary. I am not as good as Han Xin in leading troops to fight. These three people are outstanding people, and I can use them, which is an important reason why I can win the world. There is only one Fan Zeng who can't make good use of it. "It is enough to see who a leader is, depending on who he values.

Third, the way of thinking is simple and grumpy. Xianyang Palace is of course a den of murder, lust for power and pleasure for Qin Shihuang, but what are the crimes of palaces and beautiful women? You turned your anger at Ying Zheng into a fire in Xianyang Palace, but you should be careful when throwing rats. Can you burn the forest to kill wolves? Isn't Xiang Yu short of brains? Sun Tzu has a saying: "Go up and down, then attack the enemy, then attack the soldiers, and then attack the city." You despise strategy, you don't know diplomacy, you look for force, you think that power has everything, and it is absurd to enfeoffment eighteen countries as subjective hegemony. It should be noted that there is not only one mode of struggle and ending: you eat me or I eat you. Confucius said, "If you want to be a man, you want to achieve it"? The Analects of Confucius is forever. Isn't this what people often say today is "win-win"?

The fourth is military strategy. Xiang Yu's enfeoffment of princes was unfair, which prompted those princes who were dissatisfied with the enfeoffment to fall to Liu Bang, making him increasingly isolated politically. The Hongmen banquet set the tiger back to the mountain, leaving endless troubles.

Fifth, the geographical location is lost. The terrain of China is low in the east and steep in the west. From a military point of view, the steep terrain in the west is absolutely important to the war. Although Emperor Gaozu entered the customs first, because Xiang Yu came late, his troops were far stronger than Emperor Gaozu, and the Guanzhong area was once again occupied by Xiang Yu. Xiang Yu didn't realize the importance of Guanzhong. Han Sheng advised him to build the capital of Guanzhong, but he thought that "wealth does not return to his hometown, like walking at night, who can see it?" Those still in the capital were assigned to three generals, namely, Jin and Sima Xin. Sure enough, soon after Xiang Yu left Guanzhong, Emperor Gaozu sent troops to recapture Guanzhong. Emperor Gaozu knew the importance of Guanzhong, so he had to take it as a base, which was also obtained by Emperor Gaozu. Xiang Yu's loss is that he can't understand the importance of Guanzhong and lost this place. As far as military terrain is concerned, Emperor Gaozu has been in an invincible position. What's more, Guanzhong is not only rugged, but also fertile and rich in agricultural products. Emperor Gaozu fought against Xiang Yu in Guandong, taking Guanzhong as the base, and no longer worried about the shortage of rations. Coupled with the original rich places such as Bashu and Hanzhong, he can achieve sufficient materials and fight a protracted war. Xiang Yu, on the other hand, seems to have never paid much attention to the commissary building. The accumulation behind him was often burned by Peng Yue, making it impossible to continue, but he could not catch or cut off the source of reimbursement of the Han army. As a result, the Han army has always been full, and the Chu army is hungry. Undefeated Xiang Yu had to retreat and return to the East. This is another failure of Xiang Yu. )

This is a historical trend. Qin Shihuang unified the world, which was a great progress in history. Later, he conformed to the public opinion and overthrew the rule of Qin, which was also in line with the historical trend. However, Xiang Yu's "dividing the world and enfeoffing the princes" after the Qin Dynasty was destroyed, which made the society return to the turbulent state of the separatist regime before the reunification of Qin Dynasty, which was against the historical trend. After the victory of the Chu-Han War, Liu Bang imitated the Qin imperial system and established the Han empire, which was in line with the historical trend. Flourishing with the historical trend and dying against it are the fundamental reasons.