HISTORY
reat Wall of the Qin Dynasty Great Wall of the Han Dynasty Great Wall of the Ming Dynasty Map of the whole wall
constructionsThe Chinese were already familiar with the techniques of wall-building by the time of the Spring and Autumn Period, which began around the 7th century BC. During the Warring States Period from the 5th century BC to 221 BC, the states of Qi, Yan and Zhao all constructed extensive fortifications to defend their own borders. Built to withstand the attack of small arms such as swords and spears, these walls were made mostly by stamping earth and gravel between board frames. Qin Shi Huang conquered all opposing states and unified China in 221 BC, establishing the Qin Dynasty. Intending to impose centralized rule and prevent the resurgence of feudal lords, he ordered the destruction of the wall sections that 
divided his empire along the former state borders. To protect the empire against intrusions by the Xiongnu people from the north, he ordered the building of a new wall to connect the remaining fortifications along the empire's new northern frontier. Transporting the large quantity of materials required for construction was difficult, so builders always tried to use local resources. Stones from the mountains were used over mountain ranges, while rammed earth was used for construction in the plains. There are no surviving historical records indicating the exact length and course of the Qin Dynasty walls. Most of the ancient walls 
have eroded away over the centuries, and very few sections remain today. Later, the Han, Sui, Northern and Jin dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders.
The Great Wall concept was revived again during the Ming Dynasty following the Ming army's defeat by the Oirats in the Battle of Tumu in 1449. The Ming had failed to gain a clear upper-hand over the Manchurian and Mongolian tribes after successive battles, and the long-drawn conflict was taking a toll on the empire. The Ming adopted a new strategy to keep the nomadic tribes out by constructing walls along the northern border of China. Acknowledging the Mongol control established in the Ordos Desert, the wall followed the desert's southern edge instead of incorporating the bend of the Huang He.
Photograph of the Great Wall in 1907Unlike the earlier Qin fortifications, the Ming construction was stronger and more elaborate due to the use of bricks and stone instead of rammed earth. As Mongol raids continued periodically over the years, the Ming devoted considerable resources to repair and reinforce the walls. Sections near the Ming capital of Beijing were especially strong.[7] Towards the end of the Shun Dynasty, the Great Wall helped defend the empire against the Manchu invasions that began around 1600. Under the military command of Yuan Chonghuan, the Ming army held off the Manchus at the heavily fortified Shanhaiguan pass, preventing the Manchus from entering the Liaodong Peninsula and the Chinese heartland. The Manchus were finally able to cross the Great Wall in 1644, when the gates at Shanhaiguan were opened by Wu Sangui, a Ming border general who disliked the activities of rulers of the Shun Dynasty. The Manchus quickly seized Beijing, and defeated the newly founded Shun Dynasty and remaining Ming resistance, to establish the Qing Dynasty.
Under Qing rule, China's borders extended beyond the walls and Mongolia was annexed into the empire, so construction and repairs on the Great Wall were discontinued. A counterpart wall to the Great Wall in the south was erected to protect and divide the Chinese from the 'southern barbarians' called Miao (meaning barbaric and nomadic).[8]
Notable areas
An area of the sections of the Great Wall at Jinshanling The following three secti
ons are in Beijing municipality, which were renovated and which are regularly visited by modern tourists today.
"North Pass" of Juyongguan pass, known as the Badaling. When used by the Chinese to protect their land, this section of the wall has had many guards to defend China’s capital [Beijing]. Made of stone and bricks from the hills, this portion of the Great Wall is 7.8 meters (25.6 ft) high and 5 meters (16.4 ft) wide. One of the most striking sections of the Ming Great Wall is where it climbs
extremely steep slopes. It runs 11 kilometers (7 mi) long, ranges from 5 to 8 meters (16–26 ft) in height, and 6 meters (19.7 ft) across the bottom, narrowing up to 5 meters (16.4 ft) across the top. Wangjinglou is one of Jinshanling's 67 watchtowers, 980 meters (3,215 ft) above sea level. South East of Jinshanling, is the Mutianyu Great Wall which winds along lofty, cragged mountains from the southeast to the northwest for approximately 2.25 kilometers (about 1.3 miles). It is connected with Juyongguan Pass to the west and Gubeikou to the east. 25 km west of the Liao Tian Ling stands of part of Great wall which is only 2~3 stories high. According to the records of Lin Tian, the wall was not only extremely short compared to others, but it appears to be silver. Archeologists explain that the wall appears to be silver because the stone they used were from Shan Xi, where many mines are found. The stone contains extremely high metal in it causing it to appear silver. However, due to years of decay of the Great Wall, it is hard to see the silver part of the wall today. Another notable section lies near the eastern extremity of the wall, where the first pass of the Great Wall was built on the Shanhaiguan (known as the “Number One Pass Under Heaven”), the first mountain the Great Wall climbs. Jia Shan is also here, as is the Jiumenkou, which is the only portion of the wall that was built as a bridge. Shanhaiguan Great Wall is called the “Museum of the Construction of the Great Wall”, because of the Meng Jiang-Nu Temple, built during the Song Dynasty.
Characteristics
The Great Wall on a 1805 mapBefore the use of bricks, the Great Wall was
mainly built from Earth or Taipa, stones, and wood.
During the Ming Dynasty, however, bricks were heavily used in many areas of the wall, as were materials such as tiles, lime, and stone. The size and weight of the bricks made them easier to work with than earth and stone, so construction quickened. Additionally, bricks could bear more weight and endure better than rammed earth. Stone can hold under its own weight better than brick, but is more difficult to use. Consequently, stones cut in rectangular shapes were used for the foundation, inner and outer brims, and gateways of the wall. Battlements line the uppermost portion of the vast majority of the wall, with defensive gaps a little over 30 cm (one foot) tall, and about 23 cm (9 inches) wide.
Condition
The Great Wall at Mutianyu, near Beijing
While som
e portions north of Beijing and near tourist centers have been preserved
and even reconstructed, in many locations the Wall is in disrepair. Those parts might serve as a village playground or a source of stones to rebuild houses and roads.[9] Sections of the Wall are also prone to graffiti and vandalism. Parts have been destroyed because the Wall is in the way of construction.
reat Wall of the Qin Dynasty Great Wall of the Han Dynasty Great Wall of the Ming Dynasty Map of the whole wall
constructionsThe Chinese were already familiar with the techniques of wall-building by the time of the Spring and Autumn Period, which began around the 7th century BC. During the Warring States Period from the 5th century BC to 221 BC, the states of Qi, Yan and Zhao all constructed extensive fortifications to defend their own borders. Built to withstand the attack of small arms such as swords and spears, these walls were made mostly by stamping earth and gravel between board frames. Qin Shi Huang conquered all opposing states and unified China in 221 BC, establishing the Qin Dynasty. Intending to impose centralized rule and prevent the resurgence of feudal lords, he ordered the destruction of the wall sections that 
divided his empire along the former state borders. To protect the empire against intrusions by the Xiongnu people from the north, he ordered the building of a new wall to connect the remaining fortifications along the empire's new northern frontier. Transporting the large quantity of materials required for construction was difficult, so builders always tried to use local resources. Stones from the mountains were used over mountain ranges, while rammed earth was used for construction in the plains. There are no surviving historical records indicating the exact length and course of the Qin Dynasty walls. Most of the ancient walls 
have eroded away over the centuries, and very few sections remain today. Later, the Han, Sui, Northern and Jin dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders.The Great Wall concept was revived again during the Ming Dynasty following the Ming army's defeat by the Oirats in the Battle of Tumu in 1449. The Ming had failed to gain a clear upper-hand over the Manchurian and Mongolian tribes after successive battles, and the long-drawn conflict was taking a toll on the empire. The Ming adopted a new strategy to keep the nomadic tribes out by constructing walls along the northern border of China. Acknowledging the Mongol control established in the Ordos Desert, the wall followed the desert's southern edge instead of incorporating the bend of the Huang He.
Photograph of the Great Wall in 1907Unlike the earlier Qin fortifications, the Ming construction was stronger and more elaborate due to the use of bricks and stone instead of rammed earth. As Mongol raids continued periodically over the years, the Ming devoted considerable resources to repair and reinforce the walls. Sections near the Ming capital of Beijing were especially strong.[7] Towards the end of the Shun Dynasty, the Great Wall helped defend the empire against the Manchu invasions that began around 1600. Under the military command of Yuan Chonghuan, the Ming army held off the Manchus at the heavily fortified Shanhaiguan pass, preventing the Manchus from entering the Liaodong Peninsula and the Chinese heartland. The Manchus were finally able to cross the Great Wall in 1644, when the gates at Shanhaiguan were opened by Wu Sangui, a Ming border general who disliked the activities of rulers of the Shun Dynasty. The Manchus quickly seized Beijing, and defeated the newly founded Shun Dynasty and remaining Ming resistance, to establish the Qing Dynasty.
Under Qing rule, China's borders extended beyond the walls and Mongolia was annexed into the empire, so construction and repairs on the Great Wall were discontinued. A counterpart wall to the Great Wall in the south was erected to protect and divide the Chinese from the 'southern barbarians' called Miao (meaning barbaric and nomadic).[8]
Notable areas
An area of the sections of the Great Wall at Jinshanling The following three secti
ons are in Beijing municipality, which were renovated and which are regularly visited by modern tourists today."North Pass" of Juyongguan pass, known as the Badaling. When used by the Chinese to protect their land, this section of the wall has had many guards to defend China’s capital [Beijing]. Made of stone and bricks from the hills, this portion of the Great Wall is 7.8 meters (25.6 ft) high and 5 meters (16.4 ft) wide. One of the most striking sections of the Ming Great Wall is where it climbs
extremely steep slopes. It runs 11 kilometers (7 mi) long, ranges from 5 to 8 meters (16–26 ft) in height, and 6 meters (19.7 ft) across the bottom, narrowing up to 5 meters (16.4 ft) across the top. Wangjinglou is one of Jinshanling's 67 watchtowers, 980 meters (3,215 ft) above sea level. South East of Jinshanling, is the Mutianyu Great Wall which winds along lofty, cragged mountains from the southeast to the northwest for approximately 2.25 kilometers (about 1.3 miles). It is connected with Juyongguan Pass to the west and Gubeikou to the east. 25 km west of the Liao Tian Ling stands of part of Great wall which is only 2~3 stories high. According to the records of Lin Tian, the wall was not only extremely short compared to others, but it appears to be silver. Archeologists explain that the wall appears to be silver because the stone they used were from Shan Xi, where many mines are found. The stone contains extremely high metal in it causing it to appear silver. However, due to years of decay of the Great Wall, it is hard to see the silver part of the wall today. Another notable section lies near the eastern extremity of the wall, where the first pass of the Great Wall was built on the Shanhaiguan (known as the “Number One Pass Under Heaven”), the first mountain the Great Wall climbs. Jia Shan is also here, as is the Jiumenkou, which is the only portion of the wall that was built as a bridge. Shanhaiguan Great Wall is called the “Museum of the Construction of the Great Wall”, because of the Meng Jiang-Nu Temple, built during the Song Dynasty.Characteristics
The Great Wall on a 1805 mapBefore the use of bricks, the Great Wall was
mainly built from Earth or Taipa, stones, and wood.During the Ming Dynasty, however, bricks were heavily used in many areas of the wall, as were materials such as tiles, lime, and stone. The size and weight of the bricks made them easier to work with than earth and stone, so construction quickened. Additionally, bricks could bear more weight and endure better than rammed earth. Stone can hold under its own weight better than brick, but is more difficult to use. Consequently, stones cut in rectangular shapes were used for the foundation, inner and outer brims, and gateways of the wall. Battlements line the uppermost portion of the vast majority of the wall, with defensive gaps a little over 30 cm (one foot) tall, and about 23 cm (9 inches) wide.
Condition
The Great Wall at Mutianyu, near Beijing
While som
e portions north of Beijing and near tourist centers have been preserved
and even reconstructed, in many locations the Wall is in disrepair. Those parts might serve as a village playground or a source of stones to rebuild houses and roads.[9] Sections of the Wall are also prone to graffiti and vandalism. Parts have been destroyed because the Wall is in the way of construction.No comprehensive survey of the wall has been carried out, so it is not possible to say how much of it survives, especially in remote areas. Intact or repaired portions of the Wall near developed tourist areas are often frequented by sellers of tourist kitsch.
More than 60 kilometres (37 mi) of the wall in Gansu province may disappear in the next 20 years, due to erosion from sandstorms. In places, the height of the wall has been reduced from more than five meters (16.4 ft) to less than two meters. The square lookout towers that characterize the most famous images of the wall have disappeared completely. Many western sections of the wall are constructed from mud, rather than brick and stone, and thus are more susceptible to erosion.[10]
Watchtowers and barracks
WatchtowerCommunication between the army units along the length of the Great Wall, incl
uding the ability to call reinforcements and warn garrisons of enemy movements, was of high importance. Signal towers were built upon hill tops or other high points along the wall for their visibility.
Visibility from space
T
he Great Wall of China as seen in a false-color radar image from the Space Shuttle, taken in April 1994Visibility from the moonA Ripley's Believe It or Not! cartoon from May 1932 claimed that the wall is "the mightiest work of man, the only one that would be visible to the human eye from the moon," and Richard Halliburton's 1938 book Second Book of Marvels makes a similar claim, but it is not true. This belief has persisted, assuming urban legend status, and sometimes even appeared in school textbooks. Arthur Waldron, author of The Great Wall of China: From History to Myth, has speculated that the belief might go back to the fascination with the "canals" once believed to exist on Mars.
The Great Wall is a maximum 9.1m (30 ft) wide and is about the same color as the soil surrounding it. Based on the optics of resolving power (distance versus the width of the iris: a few millimetres for the human eye, metres for large telescopes) an object of reasonable contrast to its surroundings some 70 miles in diameter (1 arc-minute) would be visible to the unaided eye from the moon, whose average distance from Earth is 384,393 km (238,857 miles). The Great Wall is of course not a disc but more like a thread--it can be seen from much further than would be possible if it were simply a 30 foot disc. Still, the apparent width of the Great Wall from the moon is the same as that of a human hair viewed from 2 miles away. Not surprisingly, no lunar astronaut has ever claimed seeing the Great Wall from the moon.
Visibility from low earth orbit
A different question is whether the Wall is visible from low earth orbit, i.e an altitude
of as little as 100 miles (160 km). The consensus is that it is barely visible, and only under nearly perfect conditions; it is no more conspicuous than many other manmade objects.[11]
Astronaut William Pogue thought he had seen it from Skylab but discovered he was actually looking at the Grand Canal of China near Beijing. He spotted the Great Wall with binoculars, but said that "it wasn't visible to the unaided eye." US Senator Jake Garn claimed to be able to see the Great Wall with the naked eye from a space shuttle orbit in the early 1980s, but his claim has been disputed by several US astronauts. Chinese astronaut Yang Liwei said he could not see it at all.
Veteran US astronaut Gene Cernan has stated: "At Earth orbit of 100 miles (160 km) to 200 miles (320 km) high, the Great Wall of China is, indeed, visible to the naked eye." Ed Lu, Expedition 7 Science Officer aboard the International Space Station, adds that, "it's less visible than a lot of other objects. And you have to know where to look."
Topographic maps put together showing the location of the eastern parts of the wall between the Yellow River and the Bohai SeaNeil Armstrong stated about the view from Apollo 11: "I do not believe that, at least with my eyes, there would be any man-made object that I could see. I have not yet found somebody who has told me they've seen the Wall of China from Earth orbit. ... I've asked various people, particularly Shuttle guys, that have been many orbits around China in the daytime, and the ones I've talked to didn't see it." [12]
Leroy Chiao, a Chinese-American astronaut, took a photograph from the International Space Station that shows the wall. It was so indistinct that the photographer was not certain he had actually captured it. Based on the photograph, the China Daily later reported that the Great Wall can be seen from space with the naked eye, under favorable viewing conditions, if one knows exactly where to look.[13]
Similar claims rose in many countries on other manmade constructions (such as a highway network or a military base), and usually located within that country, with associations made to the wall usually employing the formula, "the two manmade structures visible from the space are the Great Wall of China and...".
Gallery
More than 60 kilometres (37 mi) of the wall in Gansu province may disappear in the next 20 years, due to erosion from sandstorms. In places, the height of the wall has been reduced from more than five meters (16.4 ft) to less than two meters. The square lookout towers that characterize the most famous images of the wall have disappeared completely. Many western sections of the wall are constructed from mud, rather than brick and stone, and thus are more susceptible to erosion.[10]
Watchtowers and barracks
WatchtowerCommunication between the army units along the length of the Great Wall, incl
uding the ability to call reinforcements and warn garrisons of enemy movements, was of high importance. Signal towers were built upon hill tops or other high points along the wall for their visibility.Visibility from space
T
he Great Wall of China as seen in a false-color radar image from the Space Shuttle, taken in April 1994Visibility from the moonA Ripley's Believe It or Not! cartoon from May 1932 claimed that the wall is "the mightiest work of man, the only one that would be visible to the human eye from the moon," and Richard Halliburton's 1938 book Second Book of Marvels makes a similar claim, but it is not true. This belief has persisted, assuming urban legend status, and sometimes even appeared in school textbooks. Arthur Waldron, author of The Great Wall of China: From History to Myth, has speculated that the belief might go back to the fascination with the "canals" once believed to exist on Mars.The Great Wall is a maximum 9.1m (30 ft) wide and is about the same color as the soil surrounding it. Based on the optics of resolving power (distance versus the width of the iris: a few millimetres for the human eye, metres for large telescopes) an object of reasonable contrast to its surroundings some 70 miles in diameter (1 arc-minute) would be visible to the unaided eye from the moon, whose average distance from Earth is 384,393 km (238,857 miles). The Great Wall is of course not a disc but more like a thread--it can be seen from much further than would be possible if it were simply a 30 foot disc. Still, the apparent width of the Great Wall from the moon is the same as that of a human hair viewed from 2 miles away. Not surprisingly, no lunar astronaut has ever claimed seeing the Great Wall from the moon.
Visibility from low earth orbit
A different question is whether the Wall is visible from low earth orbit, i.e an altitude
of as little as 100 miles (160 km). The consensus is that it is barely visible, and only under nearly perfect conditions; it is no more conspicuous than many other manmade objects.[11]Astronaut William Pogue thought he had seen it from Skylab but discovered he was actually looking at the Grand Canal of China near Beijing. He spotted the Great Wall with binoculars, but said that "it wasn't visible to the unaided eye." US Senator Jake Garn claimed to be able to see the Great Wall with the naked eye from a space shuttle orbit in the early 1980s, but his claim has been disputed by several US astronauts. Chinese astronaut Yang Liwei said he could not see it at all.
Veteran US astronaut Gene Cernan has stated: "At Earth orbit of 100 miles (160 km) to 200 miles (320 km) high, the Great Wall of China is, indeed, visible to the naked eye." Ed Lu, Expedition 7 Science Officer aboard the International Space Station, adds that, "it's less visible than a lot of other objects. And you have to know where to look."
Topographic maps put together showing the location of the eastern parts of the wall between the Yellow River and the Bohai SeaNeil Armstrong stated about the view from Apollo 11: "I do not believe that, at least with my eyes, there would be any man-made object that I could see. I have not yet found somebody who has told me they've seen the Wall of China from Earth orbit. ... I've asked various people, particularly Shuttle guys, that have been many orbits around China in the daytime, and the ones I've talked to didn't see it." [12]
Leroy Chiao, a Chinese-American astronaut, took a photograph from the International Space Station that shows the wall. It was so indistinct that the photographer was not certain he had actually captured it. Based on the photograph, the China Daily later reported that the Great Wall can be seen from space with the naked eye, under favorable viewing conditions, if one knows exactly where to look.[13]
Similar claims rose in many countries on other manmade constructions (such as a highway network or a military base), and usually located within that country, with associations made to the wall usually employing the formula, "the two manmade structures visible from the space are the Great Wall of China and...".
Gallery
No comments:
Post a Comment