The protagonist wants to build a fortification to keep the daily attacking parasitic ant army out of the border, in order to protect the normal economic production of "Dongyang City".

The first step in the construction of the fortifications was to select a site, which could not be too close to the "Dongyang Castle" to protect more activity areas, nor too far away to receive timely support.

The most suitable distance, estimated by the protagonist, is about 100 meters away from "Dongyang Castle".

This location is already close to the edge of most of the ant's foraging area, and only a few ants dare to continue digging deeper in search of food.

In addition, it is also very close to "Dongyang Castle", so if a large group of enemy troops appears, you can quickly get support.

The protagonist is in this roughly range, riding Xiaoqing to find a suitable location.

This range is actually not large, Xiaoqing quickly turned around the area of about 100 meters to the south, but there was no location that satisfied the protagonist.

The parasitic ants came from almost due south, so the fortifications had to be built roughly south. The south, on the other hand, is a large area of flat wilderness with grass and bushes, and there is no dangerous terrain for fortifications.

The basic point of fortification defense is to put the attacker in the highest danger possible and expose as much enemy as possible; Conversely, it is necessary to minimize the risks to defenders.

A well-designed fortification should be able to defend itself effectively for a long time with very few troops. A strong defense will allow the defender to hold on to the advantage of adequate supplies until the attacker is driven back by reinforcements who have come to relieve the siege, or the attacker is forced to evacuate if they are depleted of ammunition and suffering from illness.

Generally, fortifications will use the terrain to increase their defensive capabilities, so that the defenders can defend the fortified stronghold for a long time with a small number of troops.

For example, the Great Wall built in the Qin Dynasty is a tall, sturdy and continuous long wall built on dangerous terrain such as mountains. The Great Wall is not just a simple isolated city wall, but a defense system with the city wall as the main body and a large number of cities, barriers, pavilions and signs.

Of course, the protagonist does not have enough labor to build a Great Wall that protects all the borders of the country, nor does he have enough troops to defend the Great Wall.

All he wanted to build was a strong fortress, such as a fortress like a Japanese castle that was sturdy, could be garrisoned, and could be defended.

With the aggressive nature of parasitic ants, as long as such a fortress appeared in their path, then they would definitely find a way to destroy the defenders of the fortress before moving on. In this way, the vast area behind the fortress was protected.

Even if the parasitic ant army suddenly opens its mind and continues to advance around the fortress, it will be faced with the attack of "Dongyang City" and the fortress from both sides and will fall into a desperate situation.

At first, the protagonist prefers the design of a Japanese-style castle, to be precise, a Japanese-style mountain castle, because this kind of castle built in a critical place has a stronger defensive ability, and it takes less materials to build.

The guardians of the Japanese-style mountain castle (i.e., samurai) lived in the middle of the mountain or at the foot of the mountain in peacetime, and in wartime they fought on the castle located on the top of the mountain. The castle is built on the entire mountain, or it can be built on the top of the mountain, and the building can be built by flattening the top of the mountain to obtain open space.

For the protagonist, there are two biggest advantages of building a mountain city, one is that the most laborious earthwork is not a problem for ants, and the steep terrain of the mountain city can also largely offset the threat of silk parasites, according to the experience of previous wars, the climbing ability of silk parasites is very weak.

However, the protagonist searched several times, but did not find a suitable hill bag, so the plan to build a mountain castle had to be abandoned.

Considering the terrain, what can be built now is the flat castle. Heijo became popular with the flattening of castles in the middle and late Warring States periods of Japan, and Heijo was built with streets extending in all directions, often with convenient transportation and developed economy.

However, the defense capability of this flat-ground fortress is not outstanding, and it is necessary to build a large number of satellite cities to assist in defense nearby, and the formation of a defense system can reflect the advantage.

However, the protagonist does not need to develop this fortress into an economically developed market, and the defense power he needs most is precisely the shortcomings of Pingcheng.

If you want to build a fort with strong defenses on flat ground, there are also European-style castles for reference.

These castles are a product of the intensive wars of the European Middle Ages, when European nobles fought for land, food, livestock, and population, and the intensive wars led to the construction of more and more castles to defend their domains.

Castles in early Europe were simple wooden castles, and later developed into stone castles. Most European castles were also built with the help of reasonable terrain.

However, some European-style castles were also built on undefended plains, such as Smederevo Castle in Serbia. These castles relied on a defensive system consisting of main towers, walls, towers, moats, or moats, and were very fortified.

Before the advent of artillery, it often took only a small army to defend a castle, and besiegers needed a much larger army than the defenders to take a lot of time to conquer the castle.

In 1216, the French army spent half a month trying to capture a castle with only 13 men; The English castle of Carnarfon held out in two sieges in 1403-1404 with a minimum of 28 men; During the Crusades, the Knights' Fort in Syria withstood 12 sieges with only a small number of Knights Hospitallers until 1271, when the Egyptian army persuaded them to surrender.

However, although the European castle is highly defensive, its construction is labor-intensive and requires not only a large amount of stone, but also a year or even decades of skilled workers.

Although the protagonist knows the general structure of a European-style castle, he has neither skilled workers nor enough stones, and most importantly, it is impossible for him to spend years building such a castle.

In the end, the protagonist decides to build a new kind of fortress that combines the strengths of human history with the characteristics of ants.

The site for the construction of the fortress was chosen on a piece of clay land directly south of "Dongyang Castle", where the vegetation is sparse, which is not conducive to the hiding of enemy troops.

Moreover, the clay soil structure is stable, which is suitable for the foundation of fortifications, and it is also suitable for digging holes in the ground.

The whole fortification is a circle of half a meter in diameter, and the outermost side is a circle of deep trenches, and the inner side of the trench is an earthen embankment made of earth, and there is a flat trail on the top of the earthen embankment, which can be used by the defenders to move and attack the enemy from a high position.

Inside the earthen embankment was an open space for the assembly and movement of troops. A nest was dug down in the middle of the clearing, which was used for the garrison and the storage of shelter and food supplies.