0 1. From the sense of historical belonging, it can be found from many ancient books that Hanoi and Hue were once established as the capital of a country, but in terms of its existence time, Hanoi lasted longer than Hue. When people think about Hanoi, they naturally have a higher recognition and a unique sense of historical belonging. This is something Hue doesn't have.
02. Geographically, if we look at the relevant maps, it is not difficult to find that Hanoi is located in a delta surrounded by mountains, while Hue is located in a plain surrounded by mountains. In ancient times, people mainly communicated by land and water, unlike we have many choices now. Vietnam mostly uses water transportation. There are harbors in Hanoi and Hue, but Hue has the risk of silting up the soil. If one day you find your boat stuck in the mud and can't pull it out, it's really a heavy loss. In addition, Hue is close to the ocean, and if other countries invade the ocean, it is really impossible to prevent it. On the other hand, Hanoi is very different. The surrounding mountains are natural barriers, easy to defend but difficult to attack, and occupy an excellent position strategically. Therefore, in terms of geographical location, Hanoi has greater advantages than Hue.
As far as the degree of damage is concerned, we will find that Hanoi suffered less damage in the war than Hue. During the French colonial rule, Hanoi developed in an all-round way and laid the foundation. Later, the arrival of the Japanese did not destroy it. They recognized Hanoi's status, and Hanoi was relieved. Hue, by contrast, is not so lucky. Repeated battles and defeats have turned this place into a broken place, full of ruins and serious damage.
To sum up, we can know why Vietnam designated Hanoi as the capital from three aspects: historical ownership, geographical location and degree of destruction.