It will prevent it because the day that all of God’s creations love each other the way God intended for it to be, Moshiach will come.
A brief lesson in psychology: Hating someone who already hates you only adds to the other persons hate. Loving someone even though he hates you opens the door to the possibility of him loving you too.
If we start pointing fingers and saying they are to blame for all the fighting, we may be right. But doing so only adds to the fighting. If we can learn to love them even though we feel they are wronging us, we might have a chance at bringing peace to the world.
It isn’t our job to “prevent” fighting and harm. God and only God runs the world. He doesn’t need any help. It is of course true that he expects us to defend ourselves when under attack, but holding grudges and hate in our hearts doesn’t defend us. It adds to the attack.