After Cao Cao laid the foundation in Yecheng, why did he move his base camp from Xudu to Yecheng?
As for Cao Cao, I think there are three reasons.
First, Yecheng has both offensive and defensive functions in the military and controls the overall situation. We can see that after Yuan Shao completely occupied four states in Hebei, his center was Yecheng. And this place naturally has an important military role. I am here to talk about this Yecheng from both offensive and defensive aspects.
(1) Ye Cheng's role on the defensive end.
First of all, cities have the function of resisting foreigners. Yecheng was built by Qi Huangong in the Spring and Autumn Period, and its purpose at that time was to resist foreign enemies.
Notes on Water Classics: Originally written by Qi Huangong, so Guanzi says: Build Five Deer, Zhongmou and Ye Shouxia. Yecheng is surrounded by mountains and waters. The mountain is Taihang Mountain, and the water is Zhangshui and Huanshui, which is the natural barrier of this city.
Cao Cao not only made use of these natural landscapes, but also built a moat, making full use of Zhangshui and Huanshui, and also built three tall and solid platforms in the northwest of Yecheng-Ice Terrace, Bronze Terrace and Jinfeng Terrace. It also increased the city's defense capabilities.
(2) The role of Yecheng in the offensive end.
Because Yecheng belongs to the hinterland of Cao Cao's forces, it is difficult to see the offensive ability of Yecheng at that time. However, the location of Yecheng has the function of controlling Hebei Plain, and it is also a great deterrent to Luoyang. There has been a saying since ancient times that it is often easy to control with powers.
Second, the economy of Yecheng is developed. The state where Yecheng is located is Jizhou, the richest state in the late Eastern Han Dynasty.
At the end of the Eastern Han Dynasty, economic development was mainly reflected in grain. Jizhou, where Yecheng was located, was a big grain-producing state at that time, and the plains around Yecheng were extremely fertile under the irrigation of Zhangshui.
Moreover, we can know the wealth of Jizhou from some behaviors of Han Fu and Yuan Shao in the late Eastern Han Dynasty. When the governors begged Dong, a lot of food was provided by Hanfu. Later, Yuan Shao, jealous of Jizhou's wealth, designed and occupied Jizhou. When Cao Cao worried about food several times, he had never heard of Yuan Shao's distress in this respect. Jizhou has always been an image of a well-fed soldier.
Third, Yecheng enjoys convenient transportation and extends in all directions. As mentioned earlier, there are Zhangshui and Huanshui around Yecheng, which is convenient for water conservancy. In addition, Cao Cao also specially built Pinglu Canal, Cao Li Canal and Quanzhou Canal.
Wei County, where Yecheng is located, has always been the capital of Jizhou, and Yecheng is the capital of Wei County. As a place of governance, it is bound to have necessary connections with surrounding cities, so the traffic is very convenient.
Such convenient water transportation will further promote the economic development of Yecheng.
To sum up, because Yecheng has the function of controlling the overall situation militarily, the land and water transportation extends in all directions, and the surrounding areas have superior economic development conditions, Cao Cao managed it as the capital of his own armed separatist regime, making it not only the political center of his own regime, but also the location of ancestral temples and tombs.