The most unbeaten battle of Qin was the battle of Handan. The Battle of Handan is a war that broke out after the Battle of Changping. The war should not be started by Qin, and the general at that time suggested that Qin recuperate. However, Zhao Haoqi of Qin was determined to win the great country of Zhao. Since then, the six countries have no rivals of Qin, but things are not as simple as he thought. Finally, Zhao was executed and won the final victory. Qin's national strength has also greatly declined. In this war, Qin lost 100 thousand troops and delayed the time for Qin to unify the world.

The first reason why Qin was defeated in the Battle of Handan. That was after the battle of Changping in the state of Qin at that time, and the war was in turmoil. What is needed most at this time should be rest. Many soldiers are unwilling to continue attacking Zhao. The battle of Changping has been fought in Qin for three years, and these soldiers can no longer stand the battle.

The second reason is the battle of Changping. Qin Guokeng killed 400,000 people in Zhao, which greatly aroused the resentment of the people of Zhao. The soldiers inside are all their relatives, and the people of Zhao hate the people of Qin. They know that they can't live if they surrender, so they will fight to the death, and only victory can survive.

Bai Qi was one of the most famous generals in the Warring States Period. He knew that Zhao Haoqi should not fight this war. He tried his best to dissuade the king of Qin, but he still failed to stop his decision. Tian Lei also died because of this incident, and a generation of famous soldiers died in the power struggle. Although Qin consumed a lot of Zhao's effective strength in the battle of Changping, after all, it was fighting in Zhao's native land, and Zhao had geographical advantages and the support of the people behind it. These are all unfavorable factors to the state of Qin, but the king of Qin did not see this.