Yes, but you see, when two dogs don't find it necessary to fight over territory and food, because theyve, for example, lived together and have had plenty of food.
When the animal doesn't feel like it needs to fight, most animals wont fight. Self preservation is natural and can lead to violence across the animal kingdom. But most animals still are naturally adverse to violence. Even predators don't want to fight against something when its not their food, so they don't have to.
But when I say war isn't natural, it refers to the fact that any person with empathy (which is most people) would be adverse to war if it wasn't so normalized. Kids go off and die in wars they don't understand because thats what their parents did. Thats what you do. Thats what a man does. Violence is necessary. But for the most part, war takes empathetic people having a strong reason to believe it is necessary or OK, in order to happen. And if society/parents say "there is absolutely no excuse for war", then people will be less likely to excuse it.
Of course there will always have to be some violence to keep the sociopaths in check. But fighting is very natural across the board. Wars are uniquely human.