Beijing Daily Client | Reporter Han Mei
Recently, the team of Zhang Yukun, a professor at the School of Architecture of Tianjin University, announced that there is a physical remains of a Tumen in the Ming Great Wall section of Qinhuangdao City, Hebei Province. This is the first discovery of the physical defense facilities of the Great Wall recorded in the book "Mozi" more than 2,000 years ago.
As the most secret member of the Great Wall Secret Gate family, Tumen vividly inherits the architectural, military and cultural wisdom of the ancient Great Wall of China.
In recent years, the team has independently built a real-world 3D image platform for the entire Great Wall, and 5,500 kilometers of Great Wall content (including more than 130 hidden doors that have been identified) have been digitally presented in high definition, allowing visitors to get an immersive viewing experience without going to the Great Wall.
The 3D image platform of the Great Wall has precipitated the team's exploration and accumulation of cultural relics protection over the past 20 years, and the valuable digital assets formed by modern technical means have brought the sleeping Great Wall to life and become another example of China's cultural confidence in the new era.
Ancient military wisdom has long been neglected and misunderstood
The so-called "secret door", as the name suggests, is a door that is disguised and hidden and not made public. Its setting is for offensive and defensive needs. In terms of its scale, the gate of the Great Wall can be divided into three categories, of which the larger one is "Guan", which belongs to the important geographical gateway connecting the outside and the interior of the country in ancient times, and is generally equipped with heavy troops to gather and defend, such as Juyong Pass, Huangya Pass, etc.; Medium is "kou" (side mouth), such as Mutianyukou, Zhangjiakou, etc.; The smallest is the "secret door".
The maintenance of the nomadic economy in the north depended to a considerable extent on plundering or trading in the agrarian rich areas, and constant harassment and irregular market opening made ethnic relations inside and outside the Great Wall extremely uncertain. The purpose of repeatedly building the Great Wall by many Central Plains dynasties is to control the movement of materials, information, and personnel on the geographical aperture of the border, and to achieve an effective balance and countermeasure in military, economic, and resource aspects, so as to ensure the overall stability of the economic interlaced zone.
The secret door plays a multi-faceted role in the interaction of border ethnic groups, deeply participates in the development of grassroots society in the border areas, and affects the direction of political and economic relations inside and outside the Great Wall. The ancient military wisdom contained in the secret door and the corresponding engineering planning and construction ideas have an important impact on the economic activities inside and outside the Great Wall, and are the wisdom and culture left by the ancients.
Although the scale and passability of the facilities of the secret door are lower than those of the Great Wall "pass" and "entrance", it is still officially opened, and there is a clear distinction from small ancillary facilities such as "water gate" and "water mouth".
"Due to historical reasons, there are few remains of secret doors on the Great Wall, and they are scattered in the shadows, unknown and even ignored and misunderstood." Li Zhe, a team member, distinguished researcher and doctoral supervisor of the School of Architecture of Tianjin University, said.
The three-story enemy building of the Great Wall of Yingpan Village, Gubeikou, Luanping County, Chengde, was reported as a special enemy building type in 2012, but the role of its western cave entrance has not been further studied;
A pair of blocked coupon holes on the outer branch wall of the Jinshanling Great Wall in Luanping County was identified as a "wall arrow window" in 2013.
According to reports, the "National Ming Great Wall Resources Survey" project carried out since 2007 has carried out positioning, statistics and basic measurement of various site facilities, but the secret door has not been fully revealed as an independent type, some provinces and regions have been registered as "convenience gate", and some lots are classified as "water gate".
It has been confirmed that there are 220 hidden doors remaining on the Great Wall of the Ming Dynasty
The Great Wall is an ancient Chinese military fortification and a symbol of the splendid civilization of the Chinese nation. Due to the twists and turns of the Great Wall built by successive dynasties, how to make scientific and accurate measurements for the Great Wall has become a very challenging problem.
The team started research on the Great Wall in 2003, and began to apply UAV low-altitude information collection technology in 2004. At the end of 2018, the real-world 3D image acquisition project of the Great Wall was launched. Over the past four years, spanning 10 provinces and regions, the entire line of the Great Wall of the Ming Dynasty has been digitally mapped without blind spots, and more than 2 million photos taken by drones have been used to produce a three-dimensional database with an average centimeter-level accuracy, finally presenting the internal and external structure of the Great Wall of Ming clearly and clearly in front of the world.
The entrance to the trap door is generally 0.6 to 1.6 meters wide and 1.5 to 2.5 meters high, of which the narrowest can only accommodate a single person and the widest can be used by horses; Structurally, trapdoors can be divided into stone or wood beams and brick or stone arches.
Because the secret door should take into account the traffic efficiency and safety concealment, it is divided into two categories: direct and non-direct; And combined with the main wall, support wall, enemy building, Dengcheng Road, horse market and other facilities, derived a rich secret door traffic mode.
The pass-through trapdoor has the highest efficiency, taking into account rapid sneak attacks and daily non-military activities. However, the direct doorway lacks a means of deterrence, so it is often opened near the enemy platform/enemy building, and connected with the city road, which is convenient for officers and soldiers on the top of the wall or in the enemy building to monitor and inspect.
Today, more than 130 physical remains of the secret door have been identified, most of which are masonry sites, concentrated in Jizhen, Zhenbao, Xuanfu, Datong and other sections of Beijing-Tianjin-Hebei. The Qingming Great Wall in Shaanxi-Gansu-Ningxia is not easy to preserve due to the rammed earth structure, and only 2 secret doors have been found so far; In addition, relying on ancient public maps, 41 secret doors in the western section were sorted out.
Trapdoors generally lack their names and plaques, and about half of the 220 identified remains of trapdoors belong to this category. There are various types of trapdoors, and the official title of trapdoors can better express their hidden properties in form and function.
Non-straight-through trapdoors are the most concealed and changeable, but they are all staggered through the inside and outside openings to achieve the purpose of non-straight. The wall top, the wall inside the turning type, the wall top turning type trap door uses the two inner and outer climbing roads and the middle section of the wall roof to pass through, usually close to the enemy building to facilitate surveillance. When the enemy building is located in the middle of the two dengcheng roads, the flow line of entry and exit of the top of the wall must pass through the enemy building, which is more deterrent. The in-wall turning trap door obtains a similar deterrent effect by closing the narrow turning doorway.
The non-direct secret doors opened directly on the facades of the enemy building are higher and safer: "The platform is built under the platform, the door is moved up, and a ladder is placed outside, and the ladder is removed when it is captured, which seems to be stable." "Although the ladder is safer, it is inefficient, and for this reason, there is also the practice of opening secret doors on one or both sides of the enemy building.
"There are also real and false secret doors that deceive the enemy, the two are about 30 meters apart, and if the enemy enters the wrong way, it is to catch turtles in the urn; Some secret doors are disguised as arrow windows; Some are so hidden that they are imperceptible, the scale is small, only one person can bend over and pass sideways, and it is very tortuous. Li Zhe said.
The "true and false secret door" of Beijing Miyun Tianyun Mountain consists of a pass-through coupon cave secret door and a blocked secret door inside the door, and the two doors are only 10 meters apart. The false secret door doorway does not lead directly, but a door wall is set up inside the doorway, and if the enemy army mistakes the entrance hole, the defender can climb the wall from the inner steps to defend it condescendingly, or even climb down the door wall to meet the "real" secret door next to it.
"In addition to changing the flow line of the doorway, the location of the opening of the hole is also an important part of improving the safety and concealment of the secret door. Ming Dynasty border craftsmen also consciously used the shadowy corners of walls or enemy buildings to cover the entrance to the secret door. In addition, in order to pursue good concealment, the enemy building door hole type secret door generally chooses to open on the side and back façade. Li Zhe said that the location, style and group cooperation of the trapdoor are obtained under the premise of terrain conditions and border needs, balancing safety, economy and use efficiency, which is a vivid embodiment of the idea of "adapting measures to local conditions" of traditional buildings.
Li Zhe said that the total number of original secret doors of the Great Wall of the Ming Dynasty should significantly exceed the current record, and there are a considerable number of hidden door remains buried under the collapse of the wall or covered by plants, and will be found in the subsequent archaeology of the Great Wall and the construction of national parks.
Over 2,000 years! The "most secret secret door" appeared in Qinhuangdao
"In recent years, we have built the 'family map' of the secret door for the first time in the investigation of the Ming Great Wall, and discovered the most secret type of it - the sudden door." Li Zhe introduced that the section of the Great Wall where Tumen was discovered is located near Qinhuangdao in Hebei Province, and is the first physical discovery of Tumen recorded in history books more than 2,000 years ago.
As an ancient defense facility, there were records of similar facilities as early as the Spring and Autumn Warring States period more than 2,000 years ago, and the "Mozi Bei Tu" chapter made a special work on the Tumen, and the secret gate (Tumen) "hidden under the nine lands is dark, moving above the nine heavens is the sudden". Since then, scholars of the Tang, Song, Ming, and even Qing dynasties have written about it, but there are few modern research papers, and no corresponding objects have been found.
The Gate is the most secret exit of all the secret doors, and the outside is made of brick, which looks like the city wall from the outside, making it impossible for the enemy to distinguish. When the breakthrough door is not broken, it is completely hidden, and once it is necessary to send troops to defeat the enemy during the battle, the soldiers inside can quickly smash the surface wall, just like the egg breaks the shell, the soldier breaks through the wall, pinches the enemy on the side, and can even push the artillery out of the breakthrough door to repel the enemy.
"Although Tumen is a small facility on the Great Wall, it reflects the inheritance of the wisdom of the ancients more than 2,000 years ago." Li Zhe introduced that the doorway blocking type secret door is divided into two categories: the outer blocking type and the door internal blocking type, and the outer blocking type secret door is Mozi's so-called "protruding door".
"The city is a secret door... Do not wear five or six inches. Or in the middle of the night, when the enemy first arrived, the camp was undecided, and the elite horse jumped out of the sudden gate, striking him unprepared, and attacking him unexpectedly. That is, at the hole outside the secret door, a half-brick thick sealing wall at the level of the city wall remains, which is not flawed in peacetime, but soldiers can break through the wall and carry out surprise attacks in wartime.
"The stone city of the three passes, can be ten thousand people, open the gate for night attack", Li Zhe introduced, the ancient military wisdom contained in the gate is inherited by the Ming Great Wall, but its outer blocking layer structure is fragile and difficult to preserve, at present, the three gates have no trace, and the occasional relics in other sections are also easily mistaken for broken walls and ignored or "destructive repair".