Meng Tian was the most powerful general of the Qin dynasty. He participated in the Qin state’s final drive to unify China that resulted in the creation of the Qin dynasty in 221 b.c.e. His greatest feat was the building of the Great Wall of China, called the "Long Wall" in Chinese.
Major wall building began in China in the fourth century b.c.e. by three northern states, Qin, Zhao (Chao), and Yan (Yen), each of which faced nomads in the north. In 221 b.c.e. just after Qin completed the unification of China, General Meng was given the task of connecting existing walls and adding to them to form a unified system of defense against the nomads.
Some 300,000 men, soldiers, convicts, and corvée laborers were called up for the task, while they simultaneously fought campaigns against the Rong (Jung) and Di (Ti) barbarians. There is little detail on how he tackled the gargantuan task.
A biography of Meng in a monumental work called the Historical Records, by Sima Qian (Ssu-ma Ch’ien) in the first century b.c.e., merely said: "He ... built a Great Wall, constructing its defiles and passes in accordance with the configurations of the terrain. It started in Lin-t'ao and extended to Liao-tung, reaching a distance of more than ten thousand li. After crossing the [Yellow] River, it wound northward, touching the Yang mountains".
In addition, Meng was responsible for building a major north-south highway that connected the capital city Xianyang (Hsien-yang) northward through the Ordos desert, across the northern loop of the Yellow River, ending at Jiuyuan (Chiu-yuan) in Inner Mongolia.
Over flat land the road was more than 75 feet wide, and even over mountainous terrain it measured about 17 feet in width. Remnants of the road survive and a modern road follows approximately the same route.
This was one of a network of imperial highways, known as speedways that were built during the Qin dynasty that radiated from the capital city. The total of Qin highways was approximately 4,250 miles. They were crucial for fast movement of troops as well as trade and colonization.
In 210 b.c.e. the first emperor of Qin unexpectedly died while on an inspection trip, leaving the throne to his eldest son, Prince Fusu (Fu-su). Since 212 b.c.e. Fusu had been to duty on the Great Wall under General Meng. It was thought to be punishment for remonstrating with his father for the latter’s harsh treatment of Confucian scholars.
The emperor’s chief minister Li Si (Li Ssu) and chief eunuch Zhao Gao (Chao Kao) then conspired to alter the will, designating a weak younger son as heir and ordering both Fusu and Meng to commit suicide. Both complied with the order. Without its ablest general and with a weakling on the throne, the Qin dynasty fell to widespread rebellion.