The easiest, least bloody way to conquer another nation and culture is to COLONIZE IT WITH YOUR OWN PEOPLE AND CULTURE BEFORE YOU INVADE IT WITH YOUR TROOPS.
Our unenlightened, so called "ignorant" ancestors all knew this and were VERY careful who and how many people of other distinctly different cultures, religions, political leanings they allowed to live among them. It has to be people who WANT to embrace YOUR social system or they will make trouble and/or overwhelm and impose THEIR ways upon YOU. "Melting pots" of differing peoples DON'T WORK when no actual assimilation or "melting" is taking place.
Here and now, you who crave justice will find it awaiting you at the Cross of Christ. That's WHY God says "Vengence is MINE, I will repay", because you ALREADY HAVE "Justice" you have no right to also seek revenge.