[hutzlibu]

Sure you can murder your way to (temporary) peace. Empires did it all history long. But they could do it (mostly) openly and did not had to pretend to be nice, so they could do it consequently. Killing until the rebell spirit was crushed and enslaved.

The problem empires face today is that this behavior is not acceptable anymore and the empires have to act like they are there for the local people. So conquering, but not calling it like that and pretending to be nice while doing it. Hypocrite. And does not work so effective in terms of control. Because if you kill only those who indeed fight against you, than yes, their relatives are your next enemies etc.

Related: What Ghandi achieved in India he probably could not have done if the Nazis would have been the enemy empire as the british empire allready was bound by human rights. The Nazi Empire was not.

[jandrese]

Yeah, Empires have used intimidation to subjugate people for millennia, but they've also been prone to rebellion and collapse because nobody wants to live in fear. All it takes is a show of weakness and the fringes of the empire are up in revolt again. If you want an empire that can last you need to assimilate the people, which is difficult to do if you're trying to keep them afraid.

[blackstrips]

There are many forms of “assimilation” ...

One form invoked killing all military age males then selling of the woman and children as slaves scattering them.

Pretty common back in the day from what I read. Very low chance of revolt.

[hutzlibu]

"Pretty common back in the day from what I read. Very low chance of revolt."

Yes, but then you have to build up everything yourself. So to have a working province that can be milked soon, quite often local structures were also left intact. Important is to crush their culture/religion if you want to crush their spirit to revolt. Thats why the romans killed the druids of the gaulls and took away children of the nobles to make little romans out of them.

[philwelch]

You can also kidnap the children and raise them as your own.

[hutzlibu]

Fear is also a factor to force people to assimilate.