Helmets, armor and shields

Many factors have affected the development of personal armor throughout human history. Significant factors in the development of armor include the economic and technological necessities of armor production. For instance plate armor first appeared in Medieval Europe when water-powered trip hammers made the formation of plates faster and cheaper.In European history, well-known armor types include the lorica segmentata of the Roman legions, the chainmail shirt of the early medieval age, and the full steel plate harness worn by later Medieval and Renaissance knights, and a few key components (breast and back plates) by heavy cavalry in several European countries until the first year of World War I.

Source: Wikipedia