During Qin Dynasty many prisoners, criminals and slaves were incarcerated and they were asked to make weapons.
Step-by-step explanation:
Shang yang is well known for helping Qin in forming the military strength. He started to organise military troops into groups of ten and one member is made to be the head who would report to the head of the cavalry and thus the military strengthened due to proper communication tactics. Every soldier were held responsible for the other's safety in the team.
Qin army is famous for using Crossbow and they were specialists in it. They were also known for aggressive, violent and sudden assaults which made them to appear fearful and ferocious. Qin army was led by experienced generals who never feared death.