After Qin Shihuang unified the six countries, his ambition developed southward, so he launched the Southern Expedition War. Qin Shihuang launched three large-scale battles, that is, the war between Qin Jun and the indigenous people's army of Guangdong and Guangxi today, which is known as the "Three Certificates of Qin Shihuang's Lingnan" and is the most difficult stop in the Qin Dynasty's reunification campaign.
At that time, Guangdong and Guangxi were remote, the roads were rugged, it was inconvenient for Qin Jun to March, and the grain and equipment could not keep up with the big troops, which led to the long-term attack of Guangdong and Guangxi. Because the land is not easy to walk, Qin Huang took the water, so he ordered the excavation of a Lingqu to connect the water.
Lingqu is all artificially excavated, consisting of two canals, north and south, roughly parallel to Xiangjiang River. Lingqu connected the Yangtze River and the Pearl River, built a southeast water transportation network, and opened up the north-south water passage, which provided an important transportation passage for Qin Shihuang to conquer Lingnan. A large amount of grain and grass are transported to the battlefield by water, and soldiers have sufficient backup supplies, so they can be invincible.
In 2 14 BC, Lingqu was opened to navigation, when Qin Jun conquered Lingnan. Subsequently, Guilin, Nanhai and Xiang Jun were established one after another, and Lingnan formally joined the territory of the Qin Dynasty. Together with Minzhong County in Fujian at that time, the number of counties in the Qin Dynasty reached more than 40, making it the first unified centralized country in the history of China, and many emperors became famous in history.