A tower on the city wall used to defend the enemy.brightYao ShilinThe second volume of "Jian Zhi Bian" reads: "It is about three miles away from each other, and the surrounding water is heavy. Remove the boards of civilian houses and build the enemy platform along the wall
Also called pier, abutment and horse face, it is a building that protrudes outward from the wall of the city wall to defend against enemies on three sides. It is on the whole line of the city walldefenseKey defense facilities built on the basis of.[1]
According to the structure, enemy units can be divided into "solid enemy units" and "hollow enemy units".The solid enemy platform is not built with the wall in line, without arrow window, and only with the steps on the top of the platform;The hollow enemy tower is a hollow tower with windows on all sides built across the city wall. The city guards can live in it and store weapons and ammunition to fight against the enemy.The construction of the enemy platform greatly strengthened the defensive function of the city wall.
The Great Wall Enemy Platform is a pier built across the city wall, which is higher than the city wall.In the field survey of the Ming Dynasty Great Wall in Tangshan, there are two types of enemy units found: solid enemy units and hollow enemy units.Qian'an, Qianxi and Zunhua coexist 662 enemy units, only 3 solid ones, and the rest are hollow ones.
The solid enemy platform is not built with the same wall. There is no arrow window and only a step on the top of the platform.In Tangshan, it is mainly distributed in the north section of the Great Wall in Dalingzhai, Qianxi County, numbered 209, 212 and 213 respectively.All are located inside the city wall, basically square.The base is built with prefabricated strip stones, and the walls above the base are built to the top with rectangular green bricks in staggered joints. The whole enemy platform has obvious points from the base upward, and the walls are trapezoidal in shape from the outside surface.There are buttresses around the top of the wall, and observation holes are set on the buttresses.The bottom of No. 209 abutment is 8.55 meters long, 8.7 meters wide, 7.7 meters high, and 0.7 meters high. The parapet is stored under the abutment, 0.7 meters high.The bottom of No. 212 abutment is square, 9.4m square and 5.4m high.The bottom of 213 # abutment is 8.7m square, and the abutment height is 6.7m, of which the stone foundation height at the lower part of the wall is 1.5m.These three solid enemy towers are well preserved.
Of the 559 hollow enemy units in Tangshan, about 20% are relatively well preserved.The hollow enemy tower is a hollow tower with windows on all sides built across the Great Wall. The garrison soldiers can live in it and store weapons and ammunition to fight against the enemy.The creation of the hollow enemy station isMing Great WallAn important sign of the gradual strengthening of the defense system.The founder of the Hollow Enemy Platform is a famous general of the Ming DynastyMilitary leader famed for combat against Japanese pirate invaders。
Enemy Fortress of Xi'an City Wall
Enemy station
Xi'an City WallExtending from the city gate to both sides, there are 98 enemy towers with a width of 20 meters, a length of 12 meters, and a height equal to the top of the city every 120 meters.There are 20 east and west walls, 29 south and 29 north walls.There are buttress walls on three sides outside the enemy platform, and the buttress walls are provided with buttress openings.The buttress is one foot four inches wide (about 0.44 meters), which is convenient for throwing bricks, stones, wood, and shooting arrows to prevent the enemy from attacking the city.The distance between the two enemy platforms is 120 meters, and the intersection of fire power is 60 meters. It is just the effective range and killing range of ancient bow and arrow, crossbow, fly hook, throwing gun and other long-range and throwing weapons.Once the enemy attacks the city and climbs the wall, they can form a dense cross fire network from the front of the enemy platform to the left and right sides outside the main city wall, kill the enemy under the city, and make it difficult for the enemy to approach the city wall, thus improving the defensive function of the city wall.[1]
The ninety-eight enemy towers built in Xi'an City in the early Ming Dynasty were more than eighty-nine in 1982 due to the opening of new openings or gates in the city wall. Nine of them were damaged.Since 1983, the Xi'an Ring Construction Committee has repaired four enemy units, and the city now has 93 enemy units.[1]
Historical records
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According to the Ming History Biography of Qi Jiguang, although the Great Wall has been built since Jiajing, no piers and abutments have been built.Jiguang patrolled the fortress and discussed the building of an enemy platform, saying briefly: "The border wall of Ji Town extends for two thousand miles, and one flaw makes every hundred strong points flawed. It is useless to spend more time and money. Please cross the wall as a platform, and look at the four reaches. The platform is five zhang high, with three floors in the void, and hundreds of people living on it. There is enough food for the armoring. Let the garrison to work on the painting ground, and build one thousand and two hundred first." In Qi Jiguang's "Military Training Discipline",More clearly explained the process, construction method and purpose of creating hollow enemy barracks.He first said that the former Great Wall was relatively low and thin, so it was easy to collapse. "There were brick and stone platforms standing against the wall from time to time, and they could not help each other. The soldiers stood under the heat, rain, frost, and snow, and had no shelter. If the weapons and equipment started temporarily, they would not be sent far away; if they were collected on the wall, there would be no place to hide; the enemy was so powerful that it was difficult to stand up when they shot from high. When a block broke down, they ran away from each other. When the big force burst into the wall, nothing could resist it.Now we have built a hollow enemy station to block all the people and horses.Its system varies from three to four zhangs in height, twelve zhangs in width, and seventeen to eight zhangs in width.Where there is a rush (that is, a dangerous place), dozens of steps or one hundred steps are required;One set shall be set at a slow place or one hundred four or fifty steps, or more than two hundred steps.Two platforms help each other and stand right and left ".The way to build the platform: "Build the foundation at the lower level with the city wall, go out more than ten feet four or five feet, and go out more than five feet inside. The middle floor is empty, and there are four arrows and windows, and the upper floor is built with buildings, surrounded by battlements. The internal guards and soldiers will fire artillery to attack the enemy outside. The enemy's arrows cannot reach the enemy, and the enemy's cavalry will not dare to approach. Each unit has one commander, who is in charge of scheduling attacks.There are two deputies at the head of the platform, who are in charge of the weapons and supplies in the platform. There are three or fifty sergeants on both sides.Five sets have a total, ten sets have a total of one thousand, and they are made step by step. "After Qi Jiguang's supervision, the Great Wall Enemy Platform Project in Jizhou was completed in the fifth year of Longqing (1571).According to the Epitaph of Meng Zhuqi Gongs, Volume 59 of Collection of Supreme Letters, the total cost was only 100000 min, which saved 1.1 million yuan compared with the original estimated cost of 1.2 million yuan.From then on, on the two thousand mile long defense line from Shanhaiguan in the east to the town edge in the west (now the west of Changping County), there stood 1017 majestic enemy platforms. With the terrain, the height and the bottom were alternating, abrupt and uneven, which was spectacular.
These hollow enemy units are generally composed of upper, middle and lower parts.The lower part is the base, which is made of large strips of stone, the same height as the city wall, and the middle part is a hollow part. Some use brick walls and brick cylinder arches to bear the load, and build a connected coupon room. Some use wooden columns and wooden floors to bear the load, and the outer side is wrapped with thick brick walls, forming a larger room space on the first or second floor for soldiers to garrison and store food and weapons.The upper part is the top of the platform. In the middle of the top of most of the enemy's platforms, a building is built to shelter the city guards from the wind and rain. Some platforms are paved on the top of the platform to burn smoke and fire for alarm, but there is no building.Some of the top of the upper and lower platforms open holes between the floors, using rope ladders and wood ladders, and some of the brick walls are reserved with brick or stone stepping passages for one person only.The number of arrow windows and doors in the hollow part of the middle varies with the size of the enemy platform. Generally, three arrow windows are opened at the front and rear of each floor, two arrow windows and one door are opened at the left and right, and four or five arrow windows are opened on each side of the larger enemy platform.Villagers near the Great Wall often call enemy towers "three eye towers", "four eye towers" and "five eye towers" according to the number of arrows on each side of the tower.Some of the enemy towers of the Great Wall are not even, but independent of the wall. We call them piers and abutments.It has been found in Xifengkou Shitiao West, Xifengkou Huimin Village West and Xichengyu section, and the architectural structure of these piers and abutments is basically the same as that of the wall aligned hollow enemy towers.According to the function and internal structure of the hollow enemy platform, we classify it into six types: single tube arch without column, double tube arch with two columns, double tube arch with three columns, three tube arch with four columns, circular tube arch with four columns, and non tube arch with wooden column floor bearing. They are introduced below.
Structure explanation
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Figure 1: Plan and section of single barrel arch column free enemy platform
（1：200）
1、 Single barrel arch pillarless enemy station
A total of 18 such enemy units were found in Tangshan, mainly west of Tiemen Pass.The representative is No. 303 enemy station, which is rectangular in plane, 13.8 meters long and 7 meters wide, and is well preserved (Figure 1).The bottom of the four walls of the base of this enemy station is planed around, leveled with rectangular stones, and the upper part is paved with green bricks. The height of the base is equal to the top of the city wall. The base is divided in proportion from bottom to top, and the center of the base is filled with small stones and hill soil for compaction.The top of the base is paved with three or four layers of green bricks, and the top layer is plastered with square bricks.The whole base sits on the wall of the Great Wall, with less protruding from the inside of the wall and more protruding from the outside, which meets the operational requirements.
On the base is a cylindrical arch in the same direction as the Great Wall, with a length of 10.5 meters, a width of 4.2 meters, and a height of 1.2 meters.The wall at one end of the barrel arch is thickened and connected by step ladders. The steps are wooden, with the opening width of 0.8m. The steps are 15-17 steps, each 0.3m high and 0.25m wide.At both ends of the tube arch, one door is opened along the city wall, and the door frame is made of stone into an arch shaped arch, with a total height of 1.88 meters, a width of 0.66 meters, and a thickness of 0.27 meters.The inner arch of the door frame is 2.4m high, 1.2m wide and 1.1m thick.There are one arrow window on the outside of the two doors, five arrow windows on the inner and outer walls of the cylinder coupon arch, and perforations under the arrow windows.Each arrow window of the same enemy station has the same size and structure.
There is no column in the middle of this type of enemy platform, and the space is large, and the area is not less than 40 square meters.If one person lives in every two square meters, it can accommodate 20 soldiers and about 100 people in wartime.
Photo 1: Perforation and zigzag line angle of the lower wall of abutment top pier
The upper layer of the enemy platform is surrounded by brick buttresses, which are 0.6m high, 3m wide, 0.4m thick and 0.6m wide.There are perforations and drainage channels on the wall at the lower part of the pier, and the water channel is generally 0.60-0.80 meters protruding from the wall.There are two layers of zigzag line angles around the outer side of the bottom of the building wall (as shown in 1). The top plane is paved with two or three layers of green bricks, and the middle is built with green bricks to build a rectangular building.But now all the buildings have collapsed and the size cannot be measured.
2、 Double barrel arch and two column enemy station
Figure 2: Plan and Profile of Double barrel Arch and Two column Enemy Platform
（1：200）
Take the enemy station No. 11, Xuliukou, Qian'an County as an example.The plane is rectangular, 11.3 meters long and 10.2 meters wide (Figure 2). It is built across the city wall. The enemy platform projects 1.2 meters inward and 5 meters outward as a whole.
The bottom of the base shall be planed and compacted around the groove, leveled with rectangular stones, and then plastered with white plaster with rectangular blue bricks. The staggered joints shall be laid in a proportion of 1/10. The middle part shall be filled with crushed stones and hill soil for compaction, and filled and compacted to the top of the base with the increase of the surrounding walls.The height of the base part is generally equal to or not much different from the top of the city wall. The plane is paved with three or four layers of green bricks, and the top layer is paved with square bricks. The plane is staggered upward.
The upper part of the base has four walls, and the middle part is built into two large barrel arches, that is, two large long houses. A partition wall is formed at the left and right intersection of the two barrel arches.There are three coupon doors on the partition wall. Each coupon door is 2.5 meters high, 1.28 meters wide and 0.86 meters thick. A square brick column is formed between the two coupon doors. The bottom edge of the column is 1.8 meters long and 1.3 meters wide.On both sides of the brick column and the coupon door are two tube coupons. The tube arch is 8.2 meters long, 3 meters wide and 4.1 meters high in total.At both ends of the two barrel arches, a coupon door is placed along the city wall, with a total height of 2.2 meters and a width of 1.5 meters.One arrow window shall be opened outside the city wall, with a total height of 1m and a width of 0.6m.Three arrow windows are set on the inner and outer walls of the two barrel arches, with uniform and symmetrical positions and the same size.There is a passage on the inner wall to go upstairs. The floor opening is 0.78m wide, with 16 steps in total. Each step is 0.3m high and 0.25m wide.In this kind of enemy platform, there are also those who open a courtyard on the roof of the building to reach the top of the platform with a ladder and other tools. Some of the patios are open at the corner of the barrel arch, and some are open in the middle, generally square, 1.2 meters square.
The top plane of the enemy platform is 10.5 meters long and 9.2 meters wide. The surface is paved with square bricks. The surrounding walls have collapsed, with a residual height of 0.4-0.6 meters and a width of 0.4 meters. There is only a base site in the middle of the building, with a length of 6.72 meters, a width of 4.45 meters, and a width of 1.02 meters at the entrance of the building.
3、 Double barrel arch three column enemy station
Take No.44 enemy station at Hekou, Qian'an County as an example.The plane is rectangular, 13.7m long and 9m wide. The outside of the base is 4.2m high and the inside is 3.8m high (Figure 3).
Figure 3: Plan and Profile of Double barrel Arch and Three column Enemy Platform
（1：200）
The bottom of the base is planed and tamped, and then the rectangular stone is used to plaster the lime mud, and the surrounding is leveled.The strip stone is generally 0.8-1 m long and 0.3 m thick.After leveling, use rectangular green bricks to plaster white mortar and stagger the joints. The wall is about 1m thick, and the middle part is filled with crushed stones and mountain soil and compacted to the top.The top surface shall be paved with three or four layers of green bricks, and the top layer shall be square green bricks. The plane shall be staggered and leveled upward. The bricks around the top surface of the base shall be laid with a thickness of 1.1 meters.There are four arrow windows on the inner and outer walls. Each arrow window is basically the same size, and is built into an arch with bluestone. The inner arch of the arrow window is 1.05m wide, the arch foot is 1.6m high, the arch height is 0.5m, the thickness (depth) is 0.6m, the outer arch of the window is 0.6m wide, the arch foot is 0.5m high, the arch foot is 0.32m high, and the thickness is 0.4m.There are window sills at the bottom and window shaft holes at both ends.There are small perforations in the lower part of the arrow window, 0.3m wide and 0.4m high. There is one door on the left and right walls, and two arrow windows, both of which are on the inside, are connected to the city wall. There are stone door frames on the left and right doors, 0.27m thick, 0.66m wide, 1.52m high at the foot of the arch, and 0.35m high at the arch.Brick arches are used in the stone door frame, with a width of 1.6m, a height of 1.73m, a height of 0.7m and a thickness of 0.74m.There is a door sill at the bottom, and round door shafts on both sides of the sill, with a diameter of 9 cm, a depth of 5 cm, and a distance of 65 cm between the axle holes.On the wall near the door, there are stairs going upstairs. The opening of the stairs is 0.8m wide, and there are 15 steps. Each step is 0.3m high and 0.25m wide.There are two long tube arches in the middle of the four walls. The tube arch foot is 3.3m high, the arch height is 1.2m, and the total length is 10m.A partition wall is formed in the middle of the two barrel arches. The wall is 1.53 meters thick. There are four coupon doors on the wall, which break the partition wall into three square brick columns. The cross section of the brick columns is rectangular, with the length of 1.9 meters, 2 meters, 1.6 meters, and 1.5 meters wide. The total height of the coupon door is 2 meters, and the width is 1.14 meters. The roof of the building collapsed seriously.
4、 Three barrel arch four column enemy station
Figure 4: Plan and Profile of Three barrel Arch and Four column Enemy Platform
（1：200）
Take No. 70 enemy station near Lengkou, Qian'an County as an example.The plane is rectangular, 11.25m from north to south and 9.35m from east to west (Figure 4).The inner side of the base is 2.7m high and the outer side is 4m high.The bottom of the surrounding walls shall be first planed and compacted, and then paved with rectangular stones and white plaster. After leveling, the upper part shall be paved with long blue bricks and white plaster in staggered joints and flat masonry to the top surface of the base. After the middle is filled with crushed stones and mountain soil, the surface shall be paved with three or four layers of green bricks, and the top layer shall be paved with square bricks. The plane shall be staggered and flat upward.The four walls around the upper part of the base continue to be built with rectangular green bricks. The structure of the south wall and the north wall are basically the same. The doorway is inside the enemy platform, and two arrow windows are built outside.The doorway is arched with prefabricated stone strips to form a stone door frame. The stone strip is 0.27m thick, the door frame opening is 0.66m wide, the arch foot is 1.52m high, the arch height is 0.35m, and the door frame width is the same as the stone strip thickness.Under the frame lies the cornerstone, with a round door shaft at both ends. The shaft has a diameter of 9 cm, a depth of 5 cm, and a wheelbase of 61 cm.The cornerstone is 0.75 m wide and 0.23 m thick.The brick arch wall in the door frame is 0.74m thick, 1.73m high and 0.7m high.There are two arrow windows outside the doorway. The inside arch of the arrow window is 1.08m wide, the arch foot is 1.07m high, the arch height is 0.5m, and the depth is 0.63m.The arrow window is 1m high, 0.59m wide, 0.56m high and 0.35m high from the base plane.The outer opening of the arrow window is widened to 0.7m, the window sill is 0.4m wide, thick inside and thin outside, and the inner side is chiseled with a notch for putting a wooden frame, 7.5cm wide and 8.5cm deep. There is an arch shaped perforation 0.46m wide and 0.52m high 0.4 meters below the sill of the arrow window.There are 5 arrow windows on the east wall and 4 arrow windows on the west wall. There are perforations under each arrow window, so the size of arrow windows and perforations are basically the same.In addition, on the right wall of the arches in the arrow windows of the four walls of the enemy's platform, 1.1-1.35 meters above the plane of the base, the arches are chiseled into arrow shaped grooves with a total length of 0.45 meters and a shaft length of 0.28 meters (see 2). There are three arrow grooves in each group on the east wall, and two arrow grooves in each group on the north, south and west walls.During the investigation, this phenomenon was only found in this enemy station, but not in others.
Photo 2: Arrow groove on the wall
In the middle of the four walls are three barrel arches along the direction of the Great Wall (north and south), one barrel arch in the middle is 2.35m wide, and the barrel arches on both sides are 1.3-1.32m wide. The three barrel arches are the same height, with the arch foot of 3.3m high and the arch height of 1.2m.Two partition walls are formed between the three barrel arches. The partition wall is 0.86m thick. There are three coupon doors on the two partition walls to connect, forming four rectangular brick columns.The middle gate is wide, the two side gate is narrow, the middle gate is 2.45m wide, the arch foot is 1.25m high, the arch height is 1.3m, the two side gate is 1.24-1.26m wide, the arch foot is 1.8m high, and the arch height is 0.7m.A flue opening was found on the wall on one side of the arch door in the partition wall, which led directly to the top of the enemy platform. The flue opening was 0.4m high from the base plane, 0.2m wide and 0.2m high.
The top of the enemy platform is rectangular, 10.8 meters long from north to south and 9.5 meters wide from east to west.The top plane is paved with green bricks, and the middle part is built with a terrace, 7.24m long from north to south and 4.4m wide from east to west.The four remaining walls are 2-4 meters high and 0.68 meters thick. There is a door and window on the west wall, but they are all damaged.There are walls and buttresses around the building, but they have collapsed. Several perforations and launders can be seen in some sections.The south mountain wall of the building is 1.8m away from the south wall, the west wall is 2.85m away from the west wall, the north wall is 1.85m away from the north wall, and the east wall is 1.85m away from the east wall.Outside the west wall, there is a stairway opening for soldiers to go up and down. The opening is 0.8m wide.
Figure 5: Plan and section of circular barrel arch four column enemy platform
（1：200）
Photo 3: Enemy platform access
5、 Circular barrel arch four column enemy station
The most representative of such enemy units is the 250 enemy units in the northern section of Yumuling Pass in Qianxi County.The plane is square, 10 meters square (Figure 5).The bottom of the base of the enemy platform is planed and tamped, and white plaster is plastered with rectangular stones for leveling, and then black bricks are laid. The white plaster is plastered on the surface of the black bricks for stagger and flat masonry, and the scores are collected from bottom to top in proportion. From the side, it forms a trapezoid, narrow on the top and wide on the bottom.The middle of the four walls shall be filled with crushed stones and compacted with mountain soil to form a foundation plane.The base plane is plastered with three or four layers of green bricks, and the last layer is paved with square bricks. The surrounding brick walls continue to be stacked to form a central space. The east and west walls (the Great Wall runs east-west) are equipped with one door and two arrow windows, and both doors are connected to the city wall on the north side.The door frame is made of stone bars into arches. The stone bars are 0.23m thick, the inner opening of the door frame is 0.7m wide, the arch foot is 1.3m high, and the arch height is 0.3m (as shown in 3).The arch stone is built with three prefabricated curved stones, with the same thickness as the frame. There is a door sill under the frame, 0.48m wide, 0.2m thick outside and 0.12m thick inside.There are round holes for door shafts at both ends of the inner side, and a door sill 0.2m wide in the middle.In the doorway are brick arches, 1.17m wide, 1.6m high at the arch foot and 0.6m high at the arch foot.The south gate wall is 0.68 meters thick, and the north gate wall is widened to 1.17 meters because of the stairs on the top floor.There are two arrow windows on the outside of the city wall, and the size and shape of the arrow windows are basically the same.The arch in the window is 0.85m wide, 1.4m high and 0.5m high.The window is 0.72m deep, 0.95m from the top of the base, 0.5m wide, 0.48m high at the arch foot, 0.3m high at the arch foot, and 0.28m thick at the wall.At the bottom of the window lies the sill of the window, which is 0.4m wide and protrudes 0.12m outward from the wall.There are perforations under each arrow window, with a width of 0.3m and a height of 0.35m.There are 5 arrow windows on the south wall and 2 arrow windows on the north wall. The dimensions are the same as above.The four walls are built into a circular cylindrical arch with a width of 1.25 meters, a height of 2.6 meters and a height of 1.1 meters.There are four ticket gates in the middle, east, west, north and south. The ticket gate is 1.2 meters wide, the arch foot is 1.5 meters high, and the arch height is 0.35 meters.Four brick columns are formed by separating the four doors. There are hidden holes at the bottom of the four columns. Except the north wall, there are two small niches on the other three walls. The niches are 0.45 meters wide, 0.3 meters high, and 0.45 meters deep, 1.5 meters from the base surface.On the north wall, there are steps up the stairs. The corridor opening is 0.7 meters wide. There are brick steps, 15 steps in total.The top is square, 9.5 meters in length and 9.5 meters in width. The piers of the surrounding walls collapse, and the highest surviving height is 0.3 meters.There are perforations and water channels in some places. There are two layers of sawtooth bricks on the outside of the four walls at the bottom of the perforations, and the outlet angle of one layer of flat bricks is 5cm.The ruins of the central building are not clear, and only broken bricks can be seen on the surface.
Figure 6: Plan and section of load-bearing enemy platform with non barrel arch wood column connecting plate (1:200)
More than 10 such enemy units have been found on the Great Wall in Tangshan.Taking No.34 enemy station at Hekou, Qian'an County as an example, the plane is nearly square, 11.4 meters from north to south, and 11.5 meters from east to west (Figure 6).The building structure of the base of the enemy platform is the same as that of other enemy platforms. The grooves are planed from the bottom of the surrounding areas. After compaction, the rectangular stone strips are first used to plaster the white mortar for lining and leveling, and then the rectangular blue bricks are used to plaster the white mortar for stagger joint and flat masonry to the top.The center of the four walls of the base is filled with crushed stones and mountain soil for tamping. The surface is plastered with three or four layers of blue bricks. The top layer is square bricks. The plane is staggered and plastered upward to form the base plane. The walls are continuously built around the plane to the top.The top is supported by wooden columns and planks.The enemy barracks of such building structures are not easy to preserve and are seriously damaged (see Photo 4).
In our investigation, this enemy tower is a well preserved one, but only the east wall and the north wall are preserved, so it is not difficult to see that its overall bearing is not cylinder arch.On the walls on both sides, traces of round wooden columns with a diameter of about 0.3m were found.At the top of the inner side of the north wall and the east wall, there are still traces of wooden grooves with a width of 0.2-0.25 meters. There are 4 wooden columns on the east wall and 3 wooden columns on the north wall.There are arrow windows and doors on the wall between the wooden columns, all of which are arched. There are five arrow windows on the east wall. Their positions on the wall are different from those of other enemy platforms. Two of the five arrow windows are near the bottom and three are near the top.The lower part is 0.9m away from the base surface, and the upper part is 1.3m away from the base surface. The window size is basically the same, with an opening width of 0.45m, an arch foot height of 0.7m, and an arch height of 0.18m.There is a door on the inner side of the north wall, which cannot be measured due to serious collapse.There are 4 arrow windows on the outside, whose positions are two up and two down, and the size is the same as that of the east wall.The top has collapsed, and the situation is unclear.
Photo 4: No tube arch wooden column building load-bearing enemy site
The enemy units of the Great Wall are part of the whole defense system of the Great Wallthe Beacon TowerAnd other buildings.In areas where there are no beacon towers, the enemy towers are also places to spread the beacon.In the border garrison, the enemy has also become a strong fortress.When the enemy invades, they will mount the platform to meet the enemy. The platform is equipped with weapons and supplies, and the defenders are commanding so that the enemy cannot get close to the platform. Even if the enemy forces break into the side wall, the defenders of the enemy platform can still stick to the platform and shoot at the flanks and rear of the enemy.There are garrisoned troops under the enemy's platform to cooperate with the garrison on the platform, so that the enemy cannot break down the wall and invade.
The construction of the enemy platform greatly strengthened the defense function of the Great Wall.
