The Great Wall of China was initially built as separated walls by different states before the unification of China to protect their land from invasions. After the Qin Dynasty proved to be the most powerful and took over most of the lands, Emperor Qin Shi Huang connected several walls and built the first Great Wall of China between 220206 BC, and, thus, called 10,000 li Wall. The wall was established to prevent any invasion attempts and savage attacks by the northern nomadic tribes and dynasties. However, Genghis Khan, a known leader who united northern nomadic tribes, was able to penetrate the wall and able to conquer northern China, which spread all over the country later on. After the Mongol Empire, China was once again back to the leadership of their countrymen; this time, the Ming Dynasty emerged to be the most powerful. During the Ming Dynasty, the concept of the Great Wall was revived once again. The Ming Dynasty revived, reconstruct, and further elongated the Great Wall of China under its 10 year project. They adopted the strategies used by Mongols to penetrate the walls. They further extended it to the desert where the nomadic tribes used to came from. Unlike the earlier walls, Ming used bricks and stones instead of rammed earth to strengthen it, and devoted on reconstruction and repair of the walls as Mongols continued their attempts. This explains why others claim that the construction of the Great Wall of China was finished in 1644 under the Ming Dynasty.
723 beacon towers and 7,062 lookout towers of today complete Great Wall of China can explain that the wall was purposely built for protection reasons. As told, they were initially built as barriers between states during the Warring Period, and later between the land of Qin Dynasty and the northern dynasties. They also tactically served, although proven not successful in driving away invaders, to slow down invading attempts to penetrate into the Qins land. However, unlike other defense mechanisms of any country today, the Great Wall of China costs no amount upon building. Men that physically contributed to building the structure received no amount in hand. They were forced to labor, establishing the Great Wall during the Qin Dynasty. They were pushed to work as slaves under the reign of Emperor Qin Shi Huang. Rumors even said that thousands of workers died in fatigue and starvation, and that their bodies were buried in the wall itself. During the early times, the Great Wall of China justified its purpose of stopping war between dynasties, but not until the Mongol invaders penetrated the wall and invade most of China. To the right is a picture of a Beacon tower.
Another famous penetration in the wall was the known first Battle of Shanhai Pass in Shanhaiguan in 1644. This is a decisive battle of Qing over the Ming Dynasty, which signaled the end of the Ming Dynasty and crowned Qing to reign over China, making Qing Dynasty the last dynasty in the history of China. Additionally, conflicts again arose in the Great Wall of China between Chinese and Japanese soldiers.
During the 20th century, several bloody battles had been witnessed by the Great Wall of China; one of those was the second Battle of the Shanhai Pass. In 1901 at Shanhaiguan, the extreme eastern end of the Great Wall of China, the Chinese 626th regiment of the Northeastern Army met the Japanese 8th division using 4 armored trains and 10 tanks supported by warships of the Imperial Japanese Navys IJN 2nd Fleet with a dozen warships offshore. This battle cost the resignation of Chinese regimental commander Shi Shian, in January 3 of 1933, and lives of half of his men and around 500 Japanese soldiers, on the other hand.