It is difficult to ask Qin Shi Huang who was the greatest contributor to unifying the world and sweeping away the six kingdoms. Some people think that Lü Buwei, the state of the Qin Dynasty, was a man of outstanding ability, had a strategic mind, kept the internal affairs and diplomacy of the Qin Dynasty in an orderly manner, and made an indelible and important contribution to the cause of the qin dynasty's annexation of the six kingdoms. Some people also believe that it is the Qin generals Bai Qi and Wang Qi, who commanded thousands of troops and horses, swept across the battlefield, swept away strong enemies, and single-handedly laid the foundation for the Qin Dynasty.
In fact, both of these statements have some truth, but they are not accurate enough. As we all know, whether a country can rise to dominate or not depends entirely on its comprehensive national strength, from ancient times to the present. In ancient history, successive dynasties have based on agriculture, and food production is a well-known hard indicator of whether a country is strong or not. With enough food, the country can feed a large population, form a large army, and withstand the attrition of protracted war.
Bai Qi and Wang Qi can fight again, but it is difficult for Qiao Women to cook without rice. Since the ancient road "soldiers and horses did not move grain and grass first", there was a lack of sufficient grain and grass supply, and even the most powerful famous generals could only sigh in vain. Zhuge Liang is known as a dragon of thousands of people and a generation of wisdom saints, a set of eight arrays of maps alone in the world rarely encountered enemies, six out of Qishan but fruitless return, grain is not one of the most fundamental reasons.
Therefore, if the Qin state wants to dominate the world, sweep away the six countries, and increase grain production, it is a threshold that must be overcome. However, before and after the Qin king Yingzheng ascended the throne, the Qin state did not have such conditions. The Guanzhong Plain is known as a fertile wilderness, but because it is located in the northwest inland, the climate is dry and rainy, which has been seriously restricting the improvement of grain production and becoming an insurmountable bottleneck in the development process of the Qin Dynasty.
The appearance of a Korean craftsman unexpectedly solved the problem. South Korea is located on the east side of the Qin State, just on the road from the Qin State to the Central Plains. If the Qin army wants to unify the world, the first unlucky person will be South Korea. The Korean monarch realized this, like sitting on a needle felt, worrying day and night.
At this time, a minister presented a "tired Qin plan" to the Korean monarch. The core content of this plan is: to send a craftsman who is proficient in water conservancy to defect to the Qin state under the guise of letting him encourage the Qin king to vigorously carry out the capital construction of farmland water conservancy projects. The larger the amount of engineering, the better, the longer it drags on, the better, the more people mobilized, the better, so that the whole Qin state is caught in this protracted big project and cannot extricate itself, thus depleting the national strength of the Qin state, making the Qin state exhausted and difficult to launch foreign wars, so that South Korea can turn the crisis into safety.
The Korean monarch was unable to imagine, and hearing this plan, he could only use a dead horse as a live horse doctor, so he selected a bold and eloquent person among the Korean craftsmen, named Zheng Guo. Although Zheng Guo knew that this was extremely risky, for the sake of his motherland, he still accepted the mission with great enthusiasm and came to the Qin Kingdom to meet Yingzheng.
Zheng Guo planned a grand blueprint for water conservancy projects to Yingzheng: in the hinterland of the Guanzhong Plain, a long canal of more than 300 miles was built, "Zheng Guo Canal", which connected several major water systems such as the Jing River and the Luo River, and after success, it could irrigate more than 40,000 hectares of farmland, thus enabling the Agricultural Production and Grain Output of the Qin State to achieve a leap forward. Of course, the amount of work and the human and financial resources and time costs invested are also extremely large.
When Qin Wang Yingzheng heard this, he agreed to Zheng Guo's suggestion without hesitation, and the "Zheng Guo Canal" project was grandly launched, and after more than ten years of huge investment in the Qin State, he finally made this unprecedented water conservancy project successfully completed. The project presided over by Zheng Guo became a springboard for the Qin state to take off, and the "Historical Records" recorded that "Guanzhong was fertile, there was no fierce year, Qin was rich and strong, and the princes were killed", which clearly attributed the achievements of the Qin Dynasty in sweeping away the Six Kingdoms to the Korean craftsman Zheng Guo. Unfortunately, the Korean monarch was short-sighted, and trying to drag down the Qin state was counterproductive and helped the Qin state to quickly become stronger.
Reference: Chronicle of History