To the Zhang clan, as long as you were strong enough to throw a fist, you were old enough to be on the battlefield.
From the record Yang Qing saw, they had a few six-year-olds who joined the battle fronts a few years back. At six years old he was busy thinking of ways to give his grandfather and the other elders diarrhea while the Zhang clan had six-year-olds joining a battlefront with another kingdom. A battleground filled with hardened killers, where even being a veteran of war counted for nothing as you could easily die in the next second same as a rookie.
The calm state the eight were showing was only to be expected. One of the instructors who had been involved in the large-scale wars that the Order had been in in the early years after it was founded, back then he had been a measly early-stage core formation expert fighting against countless enemies both hidden and open.