This is a German WW1 helmet from 1916 (Stahlhelm M16). The Stahlhelm was introduced into regular service during the Verdun campaign in early 1916. Despite the design being updated twice ( the M17 and M18) it was still used until the end of the war and camouflaged on the field in 1918 with the new official patterns made by General Erich Ludendorff. This one has that camo.