Who was Meng Tian and what was his role in building the Great Wall?

Meng Tian (died 210 bce) was a prominent general serving under Shihuangdi, the first emperor of the Qin dynasty.1

His primary role in the construction of the Great Wall of China involved two major objectives:

• Garrisoning the Border: He was dispatched to the northern frontier to defend against incursions by the nomadic Xiongnu tribes.2
• Unifying the Wall: Beginning around 214 bce, he led a massive project—utilizing hundreds of thousands of soldiers and conscripted workers—to link existing defensive wall segments previously built by the states of Qin, Yan, and Zhao. This effort created a unified defensive system known as the "10,000-Li Long Wall".2

Following the death of Shihuangdi, Meng Tian was forced to take his own life due to political maneuvering by the minister Li Si and the eunuch Zhao Gao. After his death, the wall was largely left ungarrisoned and fell into disrepair.12