The use of the Great Wall

China's border troubles since ancient times often come from the north.

Therefore, the role of the Great Wall in past dynasties not only safeguarded national security, but also safeguarded the culture of China. Because the north is flat and the desert is endless, enemy cavalry can be seen everywhere. Therefore, only this continuous fortification can "limit the feet of flax."

But the Great Wall is not only a defense, but also a base for attack. Within the Great Wall, you can train troops, station grain and accumulate all military materials. Without the Great Wall behind it, several military actions since the Qin and Han Dynasties could not get out of the fortress, especially the famous soldiers Wei Qing and Huo Qubing in the period of Emperor Wu of the Han Dynasty. In the future, if the Xiongnu is defeated by Dou Xian in the battle of Jinwei Mountain (Altai Mountain in the northeast of Xinjiang Province) during the reign of Emperor Wu of the Han Dynasty, it will be an unprecedented success.

The source of information is: Mr. Luo Jialun, the former president of Tsinghua University and a master historian, wrote a preface for Mr. Huang Linshu's Investigation of the Great Wall of Qin Huang.

Huo Qubing made two expeditions to Hexi, but he was caught off guard by the Huns, and suffered repeated defeats.

See Historical Records: Biographies of Wei Qing and Huo Qubing for details.