Chimpanzees have a kind of government... and the government has an interest in war.
That's a bit of a reach, they have a "leader." Interestingly it was a female chimpanzee that led her "tribe" in a war killing the other tribes in the reason...
But A) This just underscores the impossibility of there being no "government." Groups will always have a leader, even when it's wild animals!
B) You claim "the chimpanzee government" had an interest in war, but what do you think that interest was? It's not like she was supporting a military industrial complex... so either it was personal or she felt it was necessary for her tribe's survival. So you'd need to show those reasons wouldn't come up in a "government free" society.