Boundary wars result in millions dead.

Massed opposing armies fight each other along a front.
The fighting continues for days, and millions die.
This is not trench warfare among men.
The armies are the weaver ants of African forests.
The ants are so fierce that when the battle is resolved and the boundaries of the opposing colonies have been fixed, a "no-ant’s-land" exists between them, where ants from each side do not dare to enter.