@Fleet Admiral Lee Hung @Da evil Who etc what do you think generals like Yotanwa, Moubu, Tou, Ouki, Duke Hyou would have done with the 100k prisoners?
Like Fleet Admiral Lee said, they would probably avoid prisoners by fighting in such a way that most of the soldiers just run away scattered.
But for any Qin generals stuck in this specific case, then there's only two options for those prisoners: Kill them or Release them. And when we actually analyze the context around Qin's invasion of Zhao, those generals you listed would end up having no choice but to kill them in this situation.
Before Kochou decided to focus on Kanki coming in too far, Qin's 6 GG were literally stalemated, unable to progress beyond Gyou. Can you imagine losing a big portion of your army, while on defense, then releasing 100k enemy soldiers, while you know that Ri Boku is probably going to come back and replace Kochou?? Wasting even more of your already depleted army to fight the same soldiers again, while they have a new stronger general...
That's extremely foolish... especially since Qin has a time limit for their conquest (extended because of Qin/Wei alliance, but still)
The way Hara wrote this Kanki vs. Kochou situation. It was always going to be a lose lose for Qin...
1) Don't wander too deep, but your at a stalemate.
2) Kill Kochou, but release his army, Ri Boku gets stronger.
3) Kill Kochou, kill his army that surrendered, rest is just politics
Hara is in a very tough spot with these characters. The execution will have to depend on their subtle characterization. Because Kanki is 100% in the right, but so is Ei Sei.