After Liu Bang established the Western Han dynasty, he also used troops against the Xiongnu . The result was a disastrous defeat and he was also besieged. It was called "The Siege of Baideng" in history. If it weren't for the trick , Chen Ping, and others gave him, he probably wouldn't have been able to come back. Therefore, from then on, the policy adopted by the Western Han Dynasty towards the Huns was to make peace with them. Although the two emperors Emperor Wen of Han and Emperor Han Jing started the Wenjing rule and made the Western Han Dynasty stronger, the policy towards the Xiongnu did not change. But after Emperor Wu of the Han Dynasty came to the throne, the situation changed. He changed his previous policy and became tougher on the Xiongnu. He used troops many times and defeated the Xiongnu. So, Why did Emperor Wu of the Han Dynasty insist on conquering the Xiongnu for many years even if he was accused of militarism? First, Emperor Wu of the Han Dynasty had great ambitions and wanted to realize the great cause of opening up new territories. Second, the marriage did not satisfy his ambitions, and he still harassed the borders of the Western Han Dynasty. Third, after the development of Wenjing’s rule, the Western Han Dynasty became stronger and stronger. Fourth, the marriage policy made it difficult for the emperor of the Western Han Dynasty to hold his head high, which was a shame.
The first The reason why Emperor Wu of the Han Dynasty is different from many emperors is that on the one hand, his abilities are there, and on the other hand, his ambition is very great. He is not willing to do this, hoping to expand his territory and achieve greater success. Big ambition. So, under this premise, he repeatedly used troops abroad, aggressively and aggressively conquered all directions, striving to achieve a "grand unification" situation where "the king has no outsiders". In fact, the Huns are just one of his opponents. Second The Han Dynasty has adopted a fraternal policy towards the Huns since Liu Bang, but by giving people and money, the Western Han Dynasty did not feed the Huns. The Huns still repeatedly invaded the border areas of the Western Han Dynasty, violating the peace treaty. Facts have proved that the marriage policy in the early Han Dynasty did not achieve actual results. Emperor Wu of the Han Dynasty was also aware of the previous marriage policy, and he also deeply realized that such a policy of blind compromise could not fundamentally solve the problem, so he hoped to make changes. The third After several generations of emperors in the early Han Dynasty recuperated and worked hard to govern, the Western Han Dynasty was no longer the time when the country was just founded. It can be said that the army and horses were strong and the national power was strong. And this was also the fundamental reason why Emperor Wu of the Han Dynasty was able to use troops abroad. He had the confidence to speak and use troops. That's why he dared to do this. Fourth If it is an emperor who has no fighting spirit, then forget about this matter. But Emperor Wu of the Han Dynasty was not such a person, so he kept in mind the humiliation of previous emperors. Liu Bang, the founding emperor of the Western Han Dynasty, was besieged and almost never came back. Later emperors had no choice but to accept this humiliation. After Liu Bang's death, the Huns even wrote letters to insult Empress Lu , and even left after burning the palace in a fire. This was a great shame for the Han Dynasty. Such humiliation always made the emperor of the Han Dynasty bear the burden of humiliation, hoping to change. 
