Wei Ci muttered, "This is a good idea, but the Tsing Yi Army claims that there are 200,000 members in their army. There will definitely be more captives in the future. Do you want to send all of the captives to the mines? Even though the iron ore is rich, it won't take long to finish mining."
Once the number of captives exceeded a certain threshold, it would become a huge danger. Conscript labor in mining was definitely tough. If they were to mine for the rest of their lives, it was difficult to ensure that these captives would not find ways to unite and create trouble.
There could not be an insufficient number of captives because most manual labor was done by captives. However, there could not be an excess number of captives because that would be shooting oneself in the foot instead. If one wanted to have a good reputation and become a benevolent ruler, one had to think of a way to properly arrange their future path.