Generally speaking, it refers to the short concave-convex wall on the city wall, and also refers to the fact that Quyi actors sing a few rhyming lyrics word by word. At the top and outside of the city wall, in the direction of meeting the enemy, there is a two-meter-high crib, which is used by combatants to observe the enemy and cover themselves when shooting at the enemy.
Start with the floor on the wall, build by laying bricks or stones to the height of the human chest, and then start to build the crib. The mouth of a crib is generally made into a concave-convex shape. There is a small square hole in the upper part of the crib, which is the observation hole.
The bricks on the left and right sides of the lookout cave are splayed inside and outside, which is convenient for observing the enemy and is not easy to be shot by the enemy's arrows. There is a small square hole below, which is the perforation of the bow and arrow. The bottom of the perforation is inclined downward, which is convenient for shooting the enemy at the gate.
2. Watchtower
They are similar in shape and have their own characteristics, including wall platforms for patrol and sentry duty, and enemy platforms on the upper and lower floors. The upper floor is surrounded by cribs and shooting holes, and the lower floor is a house for soldiers to stay and store materials. The distance of the fortress depends on the mountain and terrain.
They are all masonry structures, and the tops of the first and second floors are made of many arches, with ladders up and down. There are shooting ports, observation ports and water spouts on both floors, and there is a crib upstairs. The platform protrudes from the wall and closes the wall in the platform.
3. beacon tower
There are a large number of beacon towers as information transmission systems in the Great Wall system, which is the oldest but effective way of information transmission. There are two kinds of signals in ancient frontier defense alarm. In case of enemy situation, smoke is called "bonfire" during the day and fire is called "whistle" at night. Taiwan Province and Taiwan Province are connected to transmit information.
Burning smoke during the day and raising fire at night is because the sun is very strong during the day, the fire is not easy to see, and the smoke is more eye-catching; Smoke is not obvious at night, and fire can be seen far away. This is a very scientific method.
4. Guancheng
Guancheng is the most concentrated defensive stronghold on the defense line of Wan Li Great Wall. The position of Guancheng is very important, because it is chosen on a favorable defensive terrain, and it receives the effect of resisting powerful invaders with very few troops. In ancient times, it was called "one person guards it, and ten thousand people can't force it", which vividly explained the importance of Guancheng.
Guancheng along the Great Wall is large and small, with a large number. Take Guancheng, the Great Wall of the Ming Dynasty, as an example. There are nearly a thousand places, large and small. There are many small passes near some big passes. For example, there are more than a dozen small customs towns near Shanhaiguan, which together constitute the defense engineering architecture system of the Great Wall of Wan Li.
5. Castle
Castles are divided into acropolis, garrison or dry lake fort and fort, which are arranged in the Great Wall and sometimes outside the wall according to the requirements of defense system and military system.
The distance between Wei and Suocheng is about 100 Li, the circumference of Acropolis is 6-9 Li, and that of Qianhu Suocheng is 4-5 Li. Brick walls are built with horse-faced turrets, and gates are built with urns. Some also built a Moon City or Wing City, facing the urn gate, to strengthen the control of the city gate.
There are offices, barracks, houses and temples in the city. The distance between Weifang and Suocheng and the Great Wall is near or far, depending on the place with moderate position, gentle terrain and easy reclamation in the Great Wall.
Fort city or frontier fortress, the distance is about 10, and the circumference of the city is 1-3. Brick wall wrapping, opening 1-2 gate, and building the gate of the urn. There are garrison barracks, schools and temples in the city, and the distance from the frontier fortress to the Great Wall is generally less than 10. In case of alarm, you can quickly board the city.
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