As a critical piece of a warfighter's protective gear, the combat helmet has vastly improved over the years as new technology and better designs have reduced the risk of fatal blows and traumatic brain injuries.
The earliest combat helmets were made from bronze and used to protect soldiers from swords and arrows. They were heavy, crudely designed and did not fit well.
During World War I and World War II, standard helmets were made from thin steel. They provided protection mainly against shrapnel rather than shock waves. They were lighter and provided better protection than helmets from previous eras.
But at that time, soldiers were often reluctant to use their chin strap because they believed that "it was better for [the helmet] to be knocked off rather than injure the soldier's neck," said Alan Hawk, a collections manager for the National Museum of Health and Medicine, a branch of the Research Support Division in the Research & Engineering Directorate of the Defense Health Agency.
Technology and safety protocols have evolved in recent years, resulting in helmets that provide more protection from both projectiles and shock waves.