In war, people who tolerate military conscription and discipline will conquer those who're slaves to pigheaded "you're not the boss of ME!" individualism.
It'd be nice if humans would voluntarily abandon war someday. But a corollary of the First Commandment is to face facts.
Sure, right up until it leads to fragging. During the Vietnam War about a thousand superiors were killed by their subjects. You can't give someone weapons, try to force them into a suicidal mission, and not expect them to use it to stop the mission. Give someone only a hammer and everything looks like a nail...
Most of this sub thread people who are unwilling to say "yeah it's forced labor and that's fine considering the details" doing mental gymnastics to make it not forced.
Many historians now concede that there is little to no meaningful difference between various forms of feudal servitude and slavery.
Slaves in the later Roman Empire also had certain rights, including the right to buy their own freedom in many cases. That doesn’t mean they weren’t slaves.
Cattle in the USA probably have more legal protections than slaves in the Roman Empire.