This chapter concentrates on the contribution of archaeology to understanding aspects of ancient warfare, archaeological methodology, and its achievements and problems in the context of explaining how men fought and armies were organized in the ancient world. A central aspect of archaeological evidence—arms and armor—is dealt with. Roman Europe has acquired the most extensive and intensively explored archaeological data for ancient campaigns, conquests, and military occupation. The data may sometimes build year-by-year campaign maps, but most often they demonstrate the shape of conflicts, conquests, and military occupations. Roman martial culture, and especially the archaeology of arms and dress, reveals how intimately associated Roman soldiers were with the peoples against whom they fought. Moreover, it is noted that archaeology is important for evaluating the martial culture of the antagonists of Greco-Roman societies.