Armour is one of the most important parts of any soldier's equipment. This holds true today, and has been true throughout history. The technology of Armour has changed, but the principle remains the same; protect the wearer during battle. While modern Armour is mainly centered on protecting against bullets, the Armour of the medieval period was designed to protect mainly against projectiles such as spears or javelins, arrows, swords, or daggers. During the Medieval period between the 5th and 15th century, army units would wear different types of Medieval Armour depending on their role, but mostly the Armour consisted of Mail or Chain mail and much later Full plate. Medieval chain mail was a special kind of Armour which consisted of small metal rings joined together to form a closely linked protective mesh. A knight in medieval times would not last long in battle without any plate Armour due to the advancement in weaponry that was made in later medieval periods. In this respect there was no option but to advance to full plate Armour in battle situations. Without full plate Armour, knights would be quickly killed by Crossbowmen, Long bowmen and Foot soldiers. Of all medieval Armour, it is the medieval helmet called the helm in those times that has stood the test of time. Although, the materials and the purpose for which it is used has changed over time, the evolution of medieval helmets during the lengthy period of the middle ages underwent gradual changes to keep up with the improvements made to medieval weaponry. It goes without saying that medieval helmets were important for the simple reason that they protected the head from weaponry and which is why a number of models of these helmets evolved during the middle Ages.