Emperor Wu-ti was the most important emperor of the Former Han dynasty.
During his reign, the empire engaged in many foreign wars which eventually lead to significant territorial expansion, the imperial bureaucracy was expanded and standardized, and Confucian thought became the official philosophy.

Wu-ti's most important military campaigns were against the Hsiung-nu.
The Hsiung-nu were the warlike nomads inhabiting the steppes of Mongolia from Manchuria west into the Chinese Turkestan.
The Hsiung-nu were extremely powerful, highly mobile, and had experienced success in mastering the defense of Asiatic bows and horsemanship.

The Hsiung-nu posed a powerful threat to the empire of Wu-ti and challenged his combat forces, but the Hsiung-nu seemed to be no match to the strategic power of Wu-ti.

His calvary consisted of anywhere from fifty to one hundred thousand soldiers with a large infantry and supply columns. Previous emperors had not been able to raise armies of such size.

It took a lot of money to support these troops, so Wu Ti also reorganized the imperial bureaucracy. He raised taxes, nationalized many private businesses and confiscated property for the nobility.

In 138 BC, Wu Ti sent a diplomatic expedition to Central Asia to try to find allies against the Hsiung-nu.
As a result of this expedition, Chinese leaders became aware of other nations and cultures to the west of India, Persia, and somewhat of the Roman Orient. Eventually, this would lead to the Silk Road.

Wu-ti helped to institute Confucian thought which, because of his efforts, became the intellectually dominant creed. Wu-ti was so fond of Confucian thought that he created and established schools that taught only Confucian thought.

Confucianism experienced success throughout China mainly because of Wu-ti's advisor who was Tung Chung-shu.
Tung Chung-shu was the founder of the "Mandate of Heaven" idea. The "Mandate of Heaven" was the idea that a ruler was under Heaven's rule.

The success of a ruler was based upon how favorable the Heaven's looked upon him. Therefore, any ruler's success on the battlefield would be perceived as showing the favor of Heaven.

Because of his success in battle that many people recognized Wu-ti as one ruling with the supreme authority of Heaven.

Wu-ti's reign had a long lasting affect on Han China. He was able to gain control of the territory between the Yangtze and the Great Wall and roughly set the political boundaries of China. He also spread Confucian thought and tried to impress his beliefs on to the dynasty as a whole.