Chimpanzee Warfare Natural?
Oldest War Re-examined the killings at Jebel Sahaba. Unfortunately, whoever wrote the title called it a "Race War" even there is not evidence for this. Aside from that, recommended reading: click here
Giant Viking Warship: a troop carrier for 100 warriors
"Killer Instincts": a review of evolutionary theories of homicide and war in the journal Nature
More Evidence of Chimpanzee Infanticide (14 May 2007)
Massacre of Maya Leaders a Collection of Stories
Mass Graves Reveal Massacre of Maya Royalty National Geographic News (11/17/05)