I remember watching a black ant hill and a red ant hill having some sort of war in my uncle's driveway once. He was like "Check this out!" And we just sat there on the porch in lawn chairs and watched and waited for the victor. I got up close a few times to see them fighting. They're brutal, they drag around their own to help or feed on them or something and the tear apart the enemy, literally.
The red ants won, by the way. Then we sprayed, flooded and smothered both hills. It's good to be human.