In Croatia, archaeologists have discovered a mass grave dating back to the third century CE that indicates another key to Roman military strength: the diversity of its soldiers. In 2011, excavation work yielded the complete, preserved skeletons of seven adult males in a water well converted into a mass grave. This is far from the first genetically diverse mass grave discovered by archaeologists, either. Researchers cited similar burial patterns in other ancient Roman regions including Skopje, Macedonia, as well as graves tied to Napoleon’s Grand Army. If anything, it’s the genetic differences that reinforce the theory that these bodies belonged to soldiers who died in battle.