Best would be if people who eat meat, kill the animal themselves. I did it when I was fishing, when young. I was taught so by my father. I was not even aware of the violence I committed to the poor animal. Probably I blocked out those feelings. Years later when I started a vegetarian lifestyle, I became more aware.
Eating meat does shut off a part of our ability to feel compassion and empathy. It must, otherwise we would feel the pain of the animal we kill (or indirectly kill by eating it). If that part is shut off, obviously we are less in tune with our feelings. So, IMO for the world to become "peaceful" it is a must that humans become vegetarian. But I see the world as a school to learn. And like normal schools there will always be different classes and different subjects, hence I do not believe that we will get global Peace on Earth (all humans at peace) ever. Personally people can make the choice though. @stvdvRF