At the beginning, although it was said that there was a plan to alienate the state of Qin. But king Zhao asked Leyi, and Leyi recommended Zhao Kuo. It is said that Zhao Kuo was in the army and had rich experience in military affairs. Moreover, he managed the army strictly. He and his father Zhao she defeated Hu Yang, a famous general of the Qin army. They were all in awe of him and willing to listen to him. Moreover, the battle of Changping was delayed, and Zhao could not sustain it (food shortage). The king of Zhao held a pre imperial meeting to discuss the replacement of the front-line commander Lian Po. All the elites of Zhao agreed, and the only objection was that Lin Xiang just thought Zhao Kuo could not shoulder the heavy responsibility
First, Zhao Kuo, at least his military accomplishment is unanimously recognized by the whole state of Zhao.
Second, under the conditions of that time, Zhao Kuo was the only choice for the front-line commander of Zhao state.
Therefore, it's unfair to blame him for the failure of the Changping war. At least these Zhao monarchs and ministers who planned at the back should also bear the responsibility.
There was no problem with Zhao Kuo's attack -- Zhao's army was good at attacking and Qin's was good at defending. However, Lianpo was good at guarding the city. It can be seen from the battle of Handan that Lianpo was really good at guarding the city. He used 100000 old and weak soldiers to resist 400000 elite of the Qin army and lasted for three months until the United forces came to reinforce him. If Zhao Kuo had been used as a general in the beginning, the outcome of the Changping war would never have been like this.
Moreover, after Shang Yang's reform, Qin's economic strength was much stronger than Zhao's. The insistence of Lianpo made Qin unbearable, while Zhao almost collapsed. If the Qin army occupied Zhao Shangdang, it would completely control Hedong, a strategic important area. To the north, you can take Jinyang, the old capital of Zhao (now southwest of Taiyuan in Shanxi Province), and to the west, you can cross Taihang Mountain, which is a direct threat to Handan, the capital of Zhao. Moreover, the state of Qin occupied the Shangdang area of South Korea, so the Shangdang area of Zhao can't be defended without attacking.
After Zhao Kuo arrived at the front line, there were many records in historical records that he changed the front-line generals and the battlefield rules, but there was no record that he did another thing besides the above work, that is, he personally surveyed the terrain for many times. (I never deceived you. It was recorded in a history book of Wei state during the Warring States period called guangchengzi. It escaped the Qin Shihuang's burning books and pitching scholars to tell the historical truth to later generations). It can be seen that a general who would personally explore the terrain, how could he be a man who can only talk on paper?
Moreover, Zhao Kuo told Changping to fight against Baiqi, the God of war. The two men used the same tactics - they both detoured behind the enemy and cut off the way back. It's just that he's not lucky, he's successful in vain, he's failed.
The reason for Zhao Kuo's failure was that it rained and the Danhe River widened and he went back to camp. This is the key point of the first World War in Changping. During the 46 days when Changping was surrounded (remember that he only took three days' rations when he went out of the camp), however, he often took the lead in charge and killed more than half of the Qin army, but his own army was not in chaos. This is not what a man on paper can do. If Zhao Kuo does not die, the Zhao army will never surrender. A general who has been out of grain for 46 days and kept the army in order will never be a mediocre.
If Zhao Kuo breaks through the encirclement, then the one who fails is absolutely in vain. Of course, luck is not on his side. I have never been clear why 400000 troops can't move 25000 Qin's defensive back line. Due to the lack of historical data, this problem may need to be solved by later generations!