The Qin army invented new weapons to exploit their advantage of their new wall. The most deadly of these was the crossbow that could hurl an arrow 250 yards with amazing accuracy. Other weapons included iron casting techniques to produce double edged swords which would not be known in the west for some 1,300 years later. The soft bronze swords of the enemy were no match for the double-edged iron swords of the Qin army.

All of this was achieved at great economic and human costs. The emperor thought the wall would bring peace to the nation but the nation was weakened by the heavy cost of the construction. Ditches along the wall were filled with the corpses of workers who died building the wall. Deaths of wall workers are estimated to exceed one million. Some have claimed that the dead workers were entombed in the wall itself. Later investigations proved this untrue. Also decaying bodies would have weakened the structure and would not have been allowed.

No society could sustain such a terrible burden. Taxation became heavier and heavier. Some 3,500,000 people were involved in the building of the Great Wall. That was 70% of the total population of China at that time. For each worker working on the wall, six were required to feed and support them. Construction of the Qin wall became the most hated imperial project in Chinese history.

In 209 BC, only a year after the death of the Qin Emperor, millions of peasants rose up and ended the tyranny and bloodshed of wall building. The Qin Dynasty had fallen, brought down by the building of the great wall. Within ten years much of the wall was a neglected ruin. Once again the northern border was at the mercy of the northern invaders.