Although your skull provides natural protection for your brain, the cranium cannot withstand a hard impact caused by an accident or a bullet. So it is good to wear a protective helmet when such things are a risk. All sorts of helmet exist: besides the ones that protect you in traffic, armies too have their own distinctive types of helmet. When machine guns and hand grenades began to be used on a large scale in the First World War, a need arose for helmets to shield their wearers from flying shrapnel. The German steel helmet or Stahlhelm was especially iconic. It replaced the earlier Pickelhaube with its distinctive spike at the top, which was originally intended to ward off blows from sabres rather than flying bullets. The first Stahlhelm protected the head, forehead and nose, but it was very heavy. Its design was improved several times and continued to be used by the German army until 1945. The helmets worn by United Nations soldiers bear a remarkable resemblance to the old Stahlhelm. They are painted a symbolic blue colour, also known as ‘UN Blue’, ensuring that the peacekeepers or ‘Blue Helmets’ who wear them are instantly recognizable.