The passage from Antiquity to the Middle Ages has been largely studied in the light of the thesis of a gradual transformation, which is in contradiction of the previous assumption of an abrupt break due to war and general calamity. Perceiving War and the Military reassesses this historical period of transition by an investigation of the contemporary world of thought that examines the impact and significance of a permanently increasing contact with warfare and armed violence. Her studies confirm the assumption of a gradual shift, but they most of all show that the irrevocable end of the Roman Peace was a crucial factor in the late Roman world becoming gradually “medieval”.